Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Metals  

DOI： 10.2320/matertrans.mt-mla2022017

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DOI： 10.2320/matertrans.MPR2023901

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Trans Tech Publications, Ltd.  

β titanium alloys have been widely used as implantation inside the human body. Based on this, two β Ti-based medium entropy alloys (namely; Ti₄₅Zr₃₃Nb₂₂and Ti₄₀Zr₃₃Nb₂₂Mn₅_,at. %) were designed using mean bond order (Bo) and mean d-orbital energy level (Md) diagram along with the CALPHAD approaches. The two alloys showed single β phase composed of a dendritic structure. When 5 at. % of Ti was replaced by Mn in Ti₄₅Zr₃₃Nb₂₂alloy, the compressive yield strength has increased. Furthermore, the hardness was increased upon the addition of Mn. Finally, Ti₄₅Zr₃₃Nb₂₂alloy showed good cold workability and slight hardness increase upon cold rolling up to 90% reduction.

DOI： 10.4028/p-84w2s6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1557/s43578-022-00691-2

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Other Link： https://link.springer.com/article/10.1557/s43578-022-00691-2/fulltext.html

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jnoncrysol.2021.121227

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Trans Tech Publications Ltd  

Self-organized TiO2 nanotubes were generated on the surface of the designed alloy Ti- 4.7Mo-4.5Fe (TMF55) by electrochemical anodization process to investigate the effect of nanostructured on the biocompatibility. The biocompatibility of the designed alloys showed very promising results compared to those of Ti-6Al-4V ELI alloy, especially for the untreated and nanostructured surfaces of the specimens with diameter size less than 35 nm. By increasing the diameter of nanotube, the biocompatibility is decreased. The most convenient compatible alloy was in favor of TMF8 alloy, making this V-free low-cost alloy is a promising candidate for replacing the commercial Ti-6Al-4V ELI alloy in biomedical applications.

DOI： 10.4028/www.scientific.net/MSF.1016.458

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：EDP Sciences  

The effect of the addition of oxygen on the formation of microstructure cooled from the β phase of Ti-Fe alloy was examined. The alloy ingots of Ti-(4, 5, 6, 7, 8, 9 and 10) at.% Fe and Ti-8 at.% Fe-(1 and 3) at.% O were arc-melted. They were homogenized at 1200 °C for 3.6 ks and then hot-rolled at 850 °C into 1.5-mm thick sheets. The disk specimen was fabricated and then put in the differential thermal analysis (DTA) apparatus. The disk in the DTA was heated at 1000 °C for 0.6 ks in the β phase and then cooled to room temperature at a rate of 50 °C/min. The microstructure was examined by an optical microscope after the DTA experiment. In the Ti-(7 and 8) Fe alloys the ω phase formed during cooling. The addition of oxygen in the Ti-8Fe alloy promoted the β→α transformation. Furthermore, the addition of one at.% oxygen in the Ti-8Fe alloy promoted β→ω_i transformation, while the addition of three at.% oxygen suppressed the β→ω_i transformation during cooling.

DOI： 10.1051/matecconf/202032112033

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2320/matertrans.ME201908

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.msec.2019.01.133

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：日本チタン協会  

J-GLOBAL

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2355/tetsutohagane.TETSU-2018-003

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Metals (JIM)  

The effect of oxygen addition on the spinodal decomposition and hardness variation of a? martensite during aging in the Ti4at% Mo alloy was investigated.Ti4at% Mo(0, 1.0, 1.5 and 3.0)at% O alloys were arcmelted. The alloy ingots were homogenized at 1473 K for 3.6 ks and then hotrolled at 1123 K into a 1.5 mm thick sheet. Specimens were solutiontreated at 1473 K for 0.6 ks and then quenched in iced brine. The solutiontreated specimens were aged at 773 K for up to 86.4 ks. The addition of 3.0at% oxygen in the solutiontreated Ti4at% Mo alloy increased hardness about 200 Hv. The hardness of the alloys during aging at 773 K increased and then decreased showing maximum. The maximum hardness decreased as increasing in oxygen content in the alloy. A modulated structure formed in the a? martensite laths during aging due to spinodal decomposition. The wave length of modulated structure by spinodal decomposition increased as increasing in oxygen content of the alloy, resulting in decrease of maximum hardness. Oxygen addition in the alloy suppressed spinodal decomposition due to increase of elastic energy for decomposition.

DOI： 10.2320/jinstmet.J2017059

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Language：English   Publishing type：Part of collection (book)   Publisher：Elsevier Inc.  

Pearl shells, which are yielded as a waste during jewel pearl culture process at Uwajima sea in Ehime prefecture, Japan, are micro-/nanostructured composite materials alternatively consisting of organic and inorganic CaCO3 layers with nanothicknesses. Micro-/nanosized pearl particles are candidates for Ca nutrients and hydroxyapatite (HAp) formation. Iron oxide nanocubes with surfactant are self-assembled into closed packing structures. The integrated structure of thermal-imprinted glass templates with functional nanoparticles becomes a potential candidate for new therapeutic nanostructures. Magnetic Y3Fe5O12 and Fe3O4 particles prepared by either break down or built-up processes were evaluated for thermal coagulation therapy. The dissolution behavior of micrometer-sized pearl powder was also evaluated in artificial stomach acid at 37°C. Future directions of micro-/nanostructured materials are proposed for biomedical applications.

DOI： 10.1016/B978-0-323-46142-9.00004-9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Effects of a phase nucleating at a transition phase and dislocation on mechanical properties in a metastable beta titanium alloy, Ti-6.8Mo-4.5Fe-1.5Al(mass%), were investigated. Tensile test and optical, scanning, and transmission electron microscopy were used. Two-step aging promoted the precipitation of a fine a phase in grain interiors because the a phase nucleated at a transition phase of beta'. A precipitation-free zone appeared at first, but finally disappeared during aging. A specimen that included the precipitation-free zone showed lower yield strength and larger elongation than it did without the precipitation-free zone. This was because dislocation could easily glide in the precipitation-free zone, which was verified from examination of the intergranular ductile fracture surface. The transition phase of beta' promoted the disappearance of a precipitation-free zone, due to the promotion of a phase precipitation, resulting in enhancement of yield strength and deterioration of elongation. It is likely that the width of PFZ and the crystallographic orientation of beta grains determine fracture mode to be intergranular ductile, intergranular brittle or intragranular fractures. Aging after tensile deformation produced a phase precipitation at dislocation. A specific variant of a phase was selected due to a stress field around the dislocation that included a planar slip band. This resulted in the formation of a large colony of the specific a variant, while elongation deteriorated because the large colony probably facilitated crack propagation.

DOI： 10.2320/matertrans.M2016382

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Language：English   Publishing type：Research paper (international conference proceedings)  

© 2017 Trans Tech Publications, Switzerland. Dynamic recrystallization in Ti-1100 was investigated. Ti-1100 is one of near α titanium alloys and contains Si for improving high temperature mechanical properties. Ti-1100 exhibits martensitic transformation by quenching into iced brine after solid solution treatment. Hereafter specimens subjected to quenching into iced brine and to cooling in air after solid solution treatment are called IBQ specimen and AC specimen, respectively. After tensile test at high temperature, IBQ specimen exhibits morphological change from lath structure to equiaxed structure, but AC specimen does not. It is indicated that dynamic recrystallization occurs during the tensile test of IBQ specimen. Effect of silicide on the dynamic recrystallization was investigated using two specimens: one included more silicide precipitates and the other less. The former specimen shows smaller recrystallized grains than the latter. It is indicated that the specimen including more silicides exhibits smaller recrystallized grains.

DOI： 10.4028/www.scientific.net/MSF.879.1634

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

A new low-cost V-free beta titanium alloy, Ti-4.7Mo-4.5Fe (TMF55), was designed based on Bo-Md electronic parameters for biomedical applications. TMF55 alloy is almost half the raw materials cost of the commercial Ti-6Al-4V alloy. Microstructures, mechanical properties, chemical properties and cytotoxicity assessment of the alloy in different heat treatment conditions were investigated and compared to those of commercial Ti-6Al-4V alloy. The aging treatments increased the strength and hardness and decreased the ductility of the alloy. The Young's modulus and ultimate strength of the as-quenched TMF55 alloy (83 GPa and 974MPa, respectively) are more compatible than that of Ti-6Al-4V alloy (110 GPa and 900 MPa, respectively) for some biomedical applications. The electrochemical behavior of the alloy was studied using potentiodynamic polarization and electrochemical impedance techniques. The corrosion current densities and the film resistances of the alloy are in the range of 3-4 nA/cm(2) and order of 10(5) Omega cm(2), respectively, they are close to those of Ti-6Al-4V alloy. The cell viability is comparable to that of commercial Ti-6Al-4V alloy, making this V-free low-cost alloy is a promising candidate for replacing the commercial Ti-6Al-4V alloy in some biomedical applications. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.matdes.2016.02.110

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Structural materials used in radiation environments require radiation tolerance and sufficient mechanical properties in the controlled state. In order to offer SUS316L austenitic stainless steel with the assumed requirements, nanostructured SUS316L with TiC addition of 2% (SUS316L-2TiC) that is capable of exhibiting enhanced tensile ductility and flow strength sufficient for structural applications was fabricated by advanced powder metallurgical methods. The methods include MA (Mechanical Alloying), HIP (Hot Isostatic Pressing), GSMM (Grain boundary Sliding Microstructural Modification) for ductility enhancement, cold rolling at temperatures below M-d (the temperature where the martensite phase occurs by plastic deformation) for phase transformation from austenite to martensite and heat treatment for reverse transformation from martensite to austenite. It is shown that the developed SUS316L-2TiC exhibits ultrafine grains with sizes of 90-270 nm, accompanied by TiC precipitates with 20-50 nm in grain interior and 70-110 nm at grain boundaries, yield strengths of 1850 to 900 MPa, tensile strengths of 1920 to 1100 MPa and uniform elongations of 0.6-21%, respectively, depending on the heat treatment temperature after rolling at -196 degrees C. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2015.08.027

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J-GLOBAL

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© 2014 Taylor & Francis. The new welding method known as F-MAG, which has been developed based on the CO2 gas-shielded arc welding method (MAG), increases deposition rate of weld metal. The F-MAG welding method is combined with hot-wire, as has been used in TIG arc- and laser-welding methods. F-MAG is performed using hot-wire which is inserted into the rear part of the weld pool made with the leading electrode. Hot-wire melts by both electrical heating of itself and heat of the weld pool. Multi-layered weld metals were prepared using F-MAG and MAG. Microstructures and mechanical properties of both as-weld and reheated zones in the uppermost layer of the multi-layered weld metals formed with F-MAG and MAG were examined and the effects of hot-wire on microstructures and mechanical properties were analysed. Both the as-weld and reheated zones of the weld metal formed with F-MAG consisted of acicular ferrite (AF), equiaxed ferrite and so on. Both strength and elongation in as-weld and reheated zones formed with F-MAG were superior compared with those formed with MAG. It could be suggested that strength increased by refinement of AF due to increase in the concentration of alloying elements being contained in the hot-wire. Larger elongation of the weld metal in F-MAG compared with that in MAG could be analysed in terms of the Aggregate of AF Laths with nearly Parallel Slip systems between neighboring AF laths (ALPS). The number of AFs contained in an ALPS formed with FMAG is larger than that with MAG, in spite of the sizes of ALPSs formed with MAG and F-MAG being almost same. Deformation occurs over a lot of AFs in the case of finer AF formed with F-MAG through the rotation of the tensile test piece during deformation, resulting in the larger elongation.

DOI： 10.1080/09507116.2014.921065

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Effects of alpha phase nucleating at a transient phase and at dislocations on mechanical properties in a metastable beta titanium alloy, Ti-6.8Mo-4.5Fe-1.5Al(mass%), have been investigated by tensile test and optical, scanning and transmission electron microscopy. Two-step aging promotes the precipitation of fine alpha phase in grain interior because alpha phase nucleates at a transition phase of beta'. Precipitate free zone appears at first, and finally disappears during aging. A specimen including precipitate free zone shows lower yield strength and larger elongation than that without precipitate free zone because dislocation can easily glide in the precipitate free zone, which can be verified from grain-boundary ductile fracture surface. The transition phase of beta' promotes the disappearance of precipitate free zone due to the promotion of a phase precipitation, resulting in enhancement of yield strength and in deterioration of elongation. Aging after tensile deformation produces alpha phase precipitation at dislocations. A specific variant of a phase is selected due to stress field around the dislocations included in a planar slip bands, resulting in the formation of a large colony of the specific a variant. Elongation is deteriorated because the large colony probably facilitates crack propagation.

DOI： 10.2320/jinstmet.J2015040

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Influence of coexisting Al2O3 on the catalytic activity for low-temperature water-gas-shift (LT-WGS) reaction over Cu catalyst was investigated. The catalytic activity of Cu/Al2O3 catalyst increased with decreasing mesopore size when S/C ratio was 2.2, whereas the catalytic activity with S/C ratio = 4.6 increased with increasing mesopore size. IR measurement combined with kinetic study suggested that the low catalytic activity of Cu/CeO2 catalyst comes from the restriction of CO adsorption on Cu-0 by bidentate-type carbonate formed on the strong basic site of CeO2 support. On the other hand, it was found that bidentate-type carbonate was not formed on Cu/Al2O3 showing high catalytic activity for LT-WGS reaction. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2014.07.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Nanostructured tungsten (W)-based materials offer many advantages for use as plasma facing materials and components exposed to heavy thermal loads combined with irradiation with high-energy neutron and low-energy ion. This paper first presents the recent progress in nanostructured toughened, fine grained, recrystallized W materials. Thermal desorption spectrometry apparatus equipped with an ion gun has been installed in the radiation controlled area in our Center at Tohoku University to systematically investigate the effects of displacement damage due to high-energy neutron irradiation on hydrogen isotope retention in connection with the nano-or micro-structures in W-based materials. In this paper, the effects of high-energy heavy ion irradiation on deuterium retention in W with different microstructures are described as a preliminary work with the prospective view of neutron irradiation effects.

DOI： 10.1088/0031-8949/2014/T159/014032

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Homogeneous precipitation of a fine alpha phase in the beta matrix of Ti alloys is a promising method for obtaining a highly strengthened Ti-based alloy. Isothermal omega particles are known to be the nucleation sites for fine alpha-phase precipitation, but an understanding of the kinetics of alpha-phase formation on isothermal omega particles is still lacking. This study aimed to reveal the effect of isothermal omega particles on alpha-phase precipitation onset time. Two-step isothermal aging of a Ti-20 at.pct Nb alloy after solid solution treatment at 1273 K (1000 A degrees C) was carried out. The first step of the aging at 633 K (360 A degrees C) involved the formation of isothermal omega particles in the beta matrix. This was followed by a second aging step at 673 K, 723 K, and 773 K (400 A degrees C, 450 A degrees C, and 500 A degrees C) for alpha-phase precipitation. Suppression of alpha-phase nucleation on the isothermal omega particles occurred at 673 K (400 A degrees C), whereas acceleration of alpha-phase nucleation on the isothermal omega particles was observed at 723 K and 773 K (450 A degrees C and 500 A degrees C). Thermodynamic stability of the isothermal omega particles and solute partitioning were controlling factors for the alpha-phase precipitation kinetics.

DOI： 10.1007/s11661-013-2092-1

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Nanostructured tungsten (W)-based materials offer many advantages for use as plasma facing materials and components exposed to heavy thermal loads combined with irradiation with high-energy neutron and low-energy ion. This paper first presents the recent progress in nanostructured toughened, fine grained, recrystallized W materials. Thermal desorption spectrometry apparatus equipped with an ion gun has been installed in the radiation controlled area in our Center at Tohoku University to systematically investigate the effects of displacement damage due to high-energy neutron irradiation on hydrogen isotope retention in connection with the nano- or micro-structures in W-based materials. In this paper, the effects of high-energy heavy ion irradiation on deuterium retention in W with different microstructures are described as a preliminary work with the prospective view of neutron irradiation effects. © 2014 The Royal Swedish Academy of Sciences.

DOI： 10.1088/0031-8949/2014/T159/014032

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Ti-Mo based alloys have been used as biocompatible materials. Recently the positive use of inexpensive alloying elements becomes important to develop low cost Ti alloys. The purpose of the present study was to reveal the effect of Fe addition in Ti-Mo alloy on the microstructure formation and mechanical properties. Ti-(2.0, 3.0)at%Mo-(0.0~2.0)at%Fe alloys were arc-melted. The alloy buttons were hot-rolled into about 2.0 mm thick sheets at 1073-1223 K. Specimens solid-solution-treated at 1273 K in b phase field were quenched into iced brine. X-ray diffractometry was used to identify phases in the specimens. Microstructures were examined by both optical and transmission electron microscopies. Hardness and Young's modulus of the alloys were evaluated. Addition of Fe in Ti-Mo alloys promoted the formation of athermal omega and increased in hardness. As-quenched Ti-3at%Mo alloy exhibited mixture of α' and α" martensites. The Young's modulus of it was 76 GPa. Ti-2at%Mo-1at%Fe alloy, replacement of 1at%Mo (expensive) by 1at%Fe (inexpensive) from Ti-3at%Mo, also exhibited mixture of α' and α" martensites with the Young's modulus of 85 GPa. Hardness of Ti-2at%Mo-1at%Fe alloy, 329Hv, is greater than that of Ti-3at%Mo alloy, 257 Hv. Ti-2at%Mo-1at%Fe is thought to be a candidate material for a low cost bone replacement Ti alloy with low Young's modulus. © (2014) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/msf.783-786.1280

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Trans Tech Publications Ltd  

The low Young's modulus of Ti-alloys is of particular importance for biomedical applications to prevent or reduce the occurrence of stress shielding. This paper shows some ways that are used to produce new Ti-alloys with low Young's modulus for biomedical applications. The different factors that affect the Young's modulus such as the phase's stability, role of alloying elements, plastic deformation, and texturing are discussed. The low-cost and low-Young's modulus Ti-alloys (i.e., alloys composed mainly of the common elements and/or contains a minimum amount of the high-cost rare elements) are also discussed. © (2014) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/AMR.1024.308

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Effect of pre-treatments before austenitization on mechanical properties in steels has been investigated. Pre-treatments are cold rolling and isothermal holding below A1 before austenitization. Pre-treatments were performed in order to introduce dislocation network in austenite (γ), which acts as nucleation site for "bainite laths within γ grain (BWING)". During the pre-treatment of isothermal holding below A1, carbon segregation and/or carbide formation might occur at grain boundary of ferrite (α). Thin γ layer might be formed around the region where carbon segregation and/or carbide formation occurred in the beginning of austenitization. Transformation strain due to α → γ would be effectively relaxed by the deformation of thin γ film, because α had been already hardened by the cold rolling. Dislocations might be introduced dominantly into the thin γ film, and stable dislocation network even in the high temperature region of γ might be formed. BWING nucleates around the dislocation network to relax the strain field around dislocation network. BWING would nucleate also at (BWING/γ) interface cooperatively to relax the strain around the interface, resulting in the formation of "aggregate of bainite laths with nearly parallel slip systems between neighboring bainite laths (ALPS)". Larger ALPS containing a lot of BWINGs might be formed in the pre-treated steel, and improves tensile strength and toughness. © (2014) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/msf.783-786.932

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Microstructures and Vickers microhardness in AZ91 magnesium alloys without and with 1mass%Y addition fabricated by casting were investigated. Vickers microhardness increases with adding 1%Y. Microstructure in AZ91 without Y addition was analyzed to contain mainly α-Mg and Mg17Al12 by X-ray diffraction. Microstructural observations with optical, scanning and transmission electron microscopes show that microstructure consists of α-Mg dendrite, non-equilibrium eutectic Mg17Al12 and lamellar Mg17Al12. The non-equilibrium eutectic Mg17Al12 exists between α-Mg dendrites. The lamellar Mg17Al12 forms near the edge of the α-Mg dendrite arm. The lamellar Mg17Al12 has Burgers orientation relationship for α-Mg matrix. It suggests that the lamellar Mg17Al12 precipitates from Al-supersaturated region within α-Mg dendrite. Addition of Y to AZ91 hardly changes dendrite arm spacing, but decreases a size of region, where longitudinal directions of primary dendrite arms are almost parallel or a single dendrite exists. Y-addition increases nucleation site for dendrite, namely makes the unidirectionally-solidified region fine, resulting in increase in hardness. © (2014) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/msf.783-786.472

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

The growth and coarsening of Cu-particles in 18%Cr-1.5%Cu ferritic stainless steels as a function of Nb content was investigated quantitatively. The samples were solution-treated at 1250 degrees C and then isothermally aged at 700 degrees C for up to 86400 s. Fine, spherical Cu-particles nucleated and grew during aging. The radius of the Cu particles increased in proportion to the one-third power of the aging time in all the stainless steels. The radius of the Cu particles in the Nb-added stainless steels was always smaller than that in the Nb-free stainless steel. The normalized standard deviation of the size distribution of the Cu particles increased and reached saturation at a certain value during aging. The increase in the standard deviation during aging was delayed by the addition of Nb. The volume fraction of Cu particles increased and reached saturation at a certain value during aging. The addition of niobium delayed the saturation of the volume fraction of the Cu particles. The slow growth of Cu particles in Nb-added stainless steels is thought to be owing to the slow diffusion of Nb atoms from the Cu particles.

DOI： 10.2355/isijinternational.54.1697

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Effect of pre-treatment before austenitization on mechanical property in a steel has been investigated. Pre-treatment was done at 500°C for 600, 1200 and 1800s before austenitization at 1440°C for 120s. This pre-treatment was performed in order to introduce dislocation network into austenite, which acts as nucleation site for "bainite laths within austenite grain (BWING)". BWING was formed with isothermal holding at 500°C for 10s after austenitization. Micro-Vickers hardness is measured in a steel with and without pre-treatment. The steel with appropriate pre-treatment exhibits high hardness, because large amounts of BWINGs are formed. In the case of cementites in pearlite being coarsened and the distance between cementites becoming large, dislocation network is apt to be introduced into γ. The dislocation network acts as nucleation site for BWING, resulting in the suppression of formation of intergranular bainite. BWINGs strengthen the steel. © (2014) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/msf.783-786.992

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Aggregate of bainite laths with almost parallel slip systems between neighboring bainite laths, hereafter referred to as ALPS, has great effect on the improvement of mechanical properties in steels. Elongation increases remarkably with increasing the number of bainite laths within an ALPS. When a bainite lath begins to deform, the neighboring bainite lath also easily deforms to relax the deformation strain, because of good parallelism between their slip systems. Under the cooperative deformation of bainite laths, the area of interface between neighboring bainite laths increases during deformation. The increase in the area of interface between neighboring bainite laths suppresses localization of dislocations at the interface, that is, dislocation density per unit area of the interface between neighboring bainite laths hardly increases, resulting in the suppression of nucleation of cracks at the interface between neighboring bainite laths. Ductile fracture would occur along the boundary between ALPSs. It could be suggested that larger ALPS and/or ALPS consisting of large number of bainite laths induce larger elongation in steels. On the other hand, it has been reported that tensile strength increases in proportion to inverse of square root of d, the d being the average size of bainite laths [1]. In order to form fine bainite lath, dislocation network instead of inclusion in austenite was utilized as nucleation site for bainite lath. Great barriers to be overcome exist for the improvement of both strength and toughness. An idea for the improvement of both strength and toughness is shown in this study. © (2014) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/msf.783-786.926

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New welding method (F-MAG) based on CO2 gas-shielded arc welding method (MAG) was developed to increase deposition rate of weld metal. In F-MAG, filler wire (hot-wire) heated using direct-current was put into rear part of weld-pool formed with main electrode used in MAG. Multi-layered weld metals were prepared using both F-MAG and MAG. Microstructures of both as-weld and reheated zones in uppermost layer of the multi-layered weld metals were examined and the effects of microstructures on mechanical properties were analyzed. Both the asweld and reheated zones of weld metal formed with F-MAG consisted of acicular ferrite (AF) and/or equiaxed ferrite and so on. Both strength and elongation in as-weld and reheated zones formed with F-MAG were superior compared with those formed with MAG. It could be suggested that strength increased by refinement of AF due to increase in the concentration of alloy elements being contained in hot-wire. Larger elongation of weld metal in F-MAG compared with that in MAG could be analyzed in terms of the aggregate of AFs with almost parallel slip systems between neighboring AFs, hereafter referred as to ALPS. The number of AFs contained in an ALPS formed in weld metal formed with F-MAG is larger than that with MAG, in spite of the sizes of ALPSs in weld metals formed with MAG and F-MAG being almost same between them. Deformation occurs over a lot of AFs in the case of finer AF through the rotation of tensile test piece during deformation.

DOI： 10.2355/tetsutohagane.99.468

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Mitigation of embrittlement caused by recrystallization and radiation is the key issue of tungsten (W) based materials for use in the advanced nuclear system such as fusion reactor applications. In this paper, our nanostructured W materials development performed so far to solve the key issue is reviewed, including new original data. Firstly, the basic concept of mitigation of the embrittlement is shown. The approach to the concept has yielded ultra-fine grained, recrystallized (UFGR) W-(0.25-1.5) mass% TiC compacts containing fine TiC dispersoids (precipitates). The UFGR W-(0.25-1.5)% TiC exhibits favorable as well as unfavorable features from the viewpoints of microstructures and various thermo-mechanical properties including the response to neutron and ion irradiations. Most of the unfavorable features stem from insufficient strengthening of weak random grain boundaries (GBs) in the recrystallized state. The focal point on this study is, therefore, to develop a new microstructural modification method to significantly strengthen the random GBs. The method is designated as GSMM (GB Sliding-based Microstructural Modification) and has lead to the birth of toughened, fine-grained W-1.1% TiC in the recrystallized state (TFGR W-1.1TiC). The TFGRW-1.1TiC exhibits much improved thermo-mechanical properties. The applicability of TFGRW-1.1TiC to the divertor in ITER is discussed.

DOI： 10.2320/matertrans.MG201209

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In order to improve mechanical property, effects of B on microstructure and mechanical property in as-weld metals containing 2-28 wt. ppm B were examined. In B rich as-weld metal, high density of fine acicular ferrite (AF) nucleated within austenite (γ) grain, but in B-poor asweld metal, ferrite precipitated at γ grain boundaries dominantly, resulting in suppressing formation of AF. The strength in B rich as-weld metal increased with increasing the formation of AF, but elongation scarcely increased. In transmission electron micrographs, precipitates were recognized except inclusion of (Ti, Mn) - oxides in B rich as-weld metal. It could be suggested that the formation of peculiar precipitation as well as the inclusion control the mechanical properties.

DOI： 10.1002/9781118792148.ch302

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The new welding method called as F-MAG, which has been developed based on CO2 gas-shielded arc welding method (CO2 welding) increase deposition rate of weld metal. Microstructures of both as-weld- and reheated-zones in uppermost layer of the multi-layered weld metals were examined and the effects of microstructures on mechanical properties were analyzed. The both zones in weld metal formed with F-MAG consist of acicular ferrite (AF) mainly. Both strength and elongation in both zones formed with F-MAG are superior compared with those with CO2 welding. It can be suggested that strength increases by refinement of AF due to increase in the concentration of alloy elements being contained in hot-wire. Larger elongation in F-MAG could be analyzed in terms of the number of AFs contained in almost same sizes of ALPS. Deformation inherits over a lot of finer AFs, namely, larger fraction of ALPS deforms compared with the case of larger size of AFs by internal stresses around deformed AFs.

DOI： 10.1002/9781118792148.ch276

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Thin film of pure Sn is prepared through electroplating Sn on stainless steel and peeling the thin Sn electrodeposit from the stainless steel. Fine Au particles, which are greatly smaller than size of Sn grain, were deposited on Sn-film in vacuum. Both-Sn films with and without the deposition of Au particles were clamped with acrylic resin plates. It was clarified that formation of Au-Sn compounds on surface of Sn-film suppressed formation of whisker. Our idea for the mechanism of whisker formation was confirmed based on the above and former results [1-3]. Conclusion is that aggregation of both edge- and screw-dislocations in small region induces the nucleation and growth of whisker. Suppression of whisker formation could be done through avoiding the aggregation of both edge- and screw-dislocations in small region by forming fine Au-Sn compounds on the surface of Sn-film.

DOI： 10.1007/978-3-319-48764-9_256

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Ordering processes of an Al-11.7 at. pct Li alloy in the early stage of aging have been investigated quantitatively by means of a newly proposed technique to determine the degree of order in a nanoscale area by using high-resolution transmission electron microscopy (TEM). After solid solution treatment at 833 K (560 A degrees C) for 1.8 ks, the specimen was quenched into iced brine. The specimen exhibited congruent ordering. It was continuously heated at a rate of 0.17 Ks(-1) (0.17 A degrees C s(-1)). During heating to 673 K (400 A degrees C), the reactions occurred in the following sequences: progress of the congruent ordering, partition of Li atoms around the antiphase domain boundaries, phase separation into Li-rich and Li-lean regions toward equilibria, and dissolution of delta' phase.

DOI： 10.1007/s11661-012-1300-8

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Effect of dislocation behavior on formation of whisker in pure Sn has been investigated. Slip system in β-Sn was determined; slip plane is {2 1̄ 1̄) , and Burgers vector b is < 01 1̄] . The magnitude of Burgers vector is larger than the smallest interatomic spacing in β-Sn. This means that there is broad space under the extra half plane of edge dislocation. It sould be noted that pipe diffusion along the edge dislocation is enhanced in β-Sn, resulting in easy supply of Sn atoms at the root of Sn whisker [1, 2]. Si-bearing particles, which precipitate on surface of bulk Sn by heat-treatment in quartz tube, suppress the accumulation of both edge and screw dislocations to same area. It is greatly effective for the suppression of the nucleation of Sn whisker. © 2012 Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/MSF.706-709.751

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Formation of hydroxyapatite (HAp) in simulated body fluid (SBF) on heated nacre has been examined. Nacre is known as composite layer of aragonite platelets and organic materials. Nacre was obtained from the shell of Akoya pearl oyster after removing its prismatic layer. The nacre was heated up to 300°C in air and then soaked in SBF. Nacre heated at 300°C lost iridescent color and became brittle, implying that organic materials which plays a role as glue between aragonite platelets mostly disappeared by heating at 300°C. Formation of HAp particles on nacre in SBF was easier than that on pure Ti. Maximum formation rate of HAp particles was obtained on the nacre heated at 200°C. The amount of HAp particles formed on the nacre heated at 300°C is the smallest. The organic materials in nacre play a critical role for HAp formation on nacre in SBF. © 2012 Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/MSF.706-709.526

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

In this work, the focus is on the thermal shock analysis of fine- and ultra-fine-grained tungsten-based materials doped with 0.5-1.1 wt% TiC that showed in previous studies improved ductility at low temperatures and also performed well when exposed to neutrons and ions (H/He). Herein, the resistance of the material to crack formation is evaluated by applying edge-localized mode-like loads (n = 100) with an energy density of 1 MJ m(-2) at various temperatures up to 150 degrees C by means of an electron beam facility. The results indicate that the cracking threshold is significantly reduced even down to room temperature when the oxygen content is reduced and the combination of grain size, TiC particle size and distribution of TiC-particles to almost each grain boundary reaches its optimum. This is achieved by a post-manufacturing treatment of the material at 1650 degrees C using the material's superplasticity caused by grain boundary sliding at this temperature, which changes the material's microstructure from ultra-fine grains surrounded by weak grain boundaries to fine grains with significantly strengthened grain boundaries.

DOI： 10.1088/0031-8949/2011/T145/014060

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Nanostructured vanadium (V) alloys are expected to exhibit high performance under neutron irradiation environments. However, their ultra-fine or refined grains cause significant decrease in flow stress at high temperatures due to grain boundary sliding (GBS), which is the major concern for their high-temperature structural applications such as future fusion reactors. The contribution of GBS to plastic deformation is known to depend strongly on grain size (GS) and may give more significant influence on long-time creep test results than on short-time tensile test results. In order to improve the creep resistance through elucidation of the effect of GS on the uniaxial creep behavior of nanostructured V alloys, a solution and dispersion hardened V alloy, V-1.4Y-7W-9Mo-0.7TiC (in wt%), with GSs from 0.58 to 2.16μm was developed by mechanical alloying and HIP processes, followed by annealing at 1473-1773K, and creep tested at 1073K and 250MPa in vacuum. It is shown that the creep resistance of V-1.4Y-7W-9Mo-0.7TiC increases monotonically with GS: The creep life for the alloy with 2.16μm in GS is as long as 114h, which is longer by factors of 2-30 than those for the other finer grained alloys and by two orders than that for coarse-grained V-4Cr-4Ti (Nifs heat2, GS: 17.8μm) that is a primary candidate material for fusion reactor structural applications. The minimum (steady state) creep rate decreases with increasing GS as ε s∝(1/ℓ) 3, where ε s is the steady state creep rate and ℓ is the grain diameter. The observed superior creep resistance of V-1.4Y-7W-9Mo-0.7TiC is discussed in terms of GS effects on dislocation glide/climb, GBS, and strain hardening capability enhanced by solution and dispersion hardening. © 2011 Elsevier B.V.

DOI： 10.1016/j.msea.2011.06.033

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Microstructure formation in V-1.6Y during neutron irradiation at 800 °C was examined with transmission electron microscopy. Faulted vacancy loops were observed in the coarse grains several micrometers in diameter without dispersed Y2O3 particles. The habit plane of the faulted vacancy loop is close to {1 1 6}. Formation of faulted vacancy loops in the vanadium matrix could be induced by oxygen picked up from the environment during irradiation. Denuded zone of faulted vacancy loops was observed around both helical dislocations and grain boundaries. © 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2011.01.068

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B4C-CeO2 composite ceramics with various concentrations of CeO2 were fabricated by hot press. The effects of CeO2 on the microstructures and mechanical properties of the B 4C-CeO2 ceramics have been investigated. During hot press, CeB6 was formed by the reaction between CeO2 and B 4C. The B4C-CeO2 ceramics had higher levels of density, fracture toughness, flexural strength and Vickers hardness than those in monolithic B4C. The microstructures of the B4C-CeO 2 ceramics were observed and analyzed by transmission electron microscopy. In-situ synthesized CeB6 indicated whisker-like shape and grew along the interface with B4C, and different boron carbides with different content of C existed at/around the interface of CeB6 with B4C in the composite ceramics. It made mechanical properties greatly improved. © 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2010.12.093

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Effects of additions of CeO2 and La2O3 on microstructure and mechanical properties of B4C fabricated under and without hot press have been investigated. Vickers hardness and fracture strength are increased by hot press due to the reduction of porosity because the sintering rate is enhanced. Hardness is increased by the reduction of porosity because crack probably occurs when the hardness is measured due to pore as an initiation point of crack. Hardness increases with increasing additions of CeO2 and La2O3 because porosity decreases due to the formation of CeB6 and LaB6 on the grain boundary of B4C, respectively. The borides are formed through reaction between solid phases, which might induce coherent boundary between boride and B 4C. Such coherency also contributes to strengthening the grain boundary of B4C. The addition of CeO2 enhances the sintering rate more than that of La2O3, resulting in higher hardness of B4C-CeO2 than that of B 4C-La2O3. © 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2011.01.072

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Effects of plastic working and the mechanical-alloying atmosphere on microstructures of ultrafine-grained, particle-dispersed W-1.1%TiC compacts, which were developed by powder metallurgical methods, have been investigated by transmission electron microscopy. Plastic working increases the density of the compacts by the reduction of number density of Ar bubbles and pores. Plastic working (PW) enhances the precipitation of TiC at weak grain boundaries of W grains. The precipitated TiC dispersoids have a Kurdjumov-Sachs orientation relationship with the W matrix, thereby significantly strengthening weak grain boundaries of W grains. Such strengthening of weak grain boundaries has not been achieved by hot isostatic pressing irrespective of its temperature. The significant improvement in fracture strength and ductility by PW is primarily due to the strengthening of weak grain boundaries and secondarily due to the decrease in Ar bubbles and pores at grain boundaries. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2010.12.117

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Creep resistance is the major concern of vanadium and its alloys for fusion reactor structural applications. In order to elucidate the effects of grain size on the creep behavior of solution and dispersion strengthened vanadium alloys. V-1.6Y-8W-0.8TiC specimens with fine grain sizes from 0.58 to 1.45 mu m were prepared by mechanical alloying and HIP without any plastic working and tested at 1073 K and 250 MPa in vacuum. It is shown that the creep resistance of V-1.6Y-8W-0.8TiC depends strongly on grain size and increases with increasing grain size: The creep life for the grain size of 1.45 mu m is almost one order longer than that of 0.58 mu m, and about two orders longer than that of V-4Cr-4Ti (NIFS-Heat 2) although the grain size of V-4Cr-4Ti is as large as 17.8 mu m. The observed creep behavior is discussed in terms of grain size effects on dislocation glide and grain boundary sliding. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2010.12.105

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In this work, the focus is on the thermal shock analysis of fine- and ultra-fine-grained tungsten-based materials doped with 0.5-1.1 wt% TiC that showed in previous studies improved ductility at low temperatures and also performed well when exposed to neutrons and ions (H/He). Herein, the resistance of the material to crack formation is evaluated by applying edge-localized mode-like loads (n=100) with an energy density of 1 MJ m -2 at various temperatures up to 150°C by means of an electron beam facility. The results indicate that the cracking threshold is significantly reduced even down to room temperature when the oxygen content is reduced and the combination of grain size, TiC particle size and distribution of TiC-particles to almost each grain boundary reaches its optimum. This is achieved by a post-manufacturing treatment of the material at 1650°C using the material's superplasticity caused by grain boundary sliding at this temperature, which changes the material's microstructure from ultra-fine grains surrounded by weak grain boundaries to fine grains with significantly strengthened grain boundaries. © 2011 The Royal Swedish Academy of Sciences.

DOI： 10.1088/0031-8949/2011/T145/014060

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Ultra-fine grained (UFG) W-TiC compacts fabricated by powder metallurgical methods utilizing mechanical alloying (MA) are very promising for use in irradiation environments. However, the assurance of room-temperature ductility and enhancement in surface resistances to low-energy hydrogen irradiation are unsettled issues. As an approach to solution to these, microstructural modification by hot plastic working has been applied to UFG W-TiC processed by MA in a purified Ar or H2 atmosphere and hot isostatic pressing (HIP). Hot plastically worked compacts have been subjected to 3-point bend tests at room temperature and TEM microstructural examinations. It is found that the microstructural modification allows us to convert UFG W-1.1%TiC to compacts exhibiting a very high fracture strength and appreciable ductility at room temperature. The compacts of W-1.1%TiC/Ar (MA atmosphere: Ar) and W-1.1%TiC/H2 (MA atmosphere: H2) exhibit re-crystallized structures with approximately 0.5 and 1.5 μm in grain size, respectively. It is shown that the enhancement of fracture resistance by microstructural modifications is attributed to significant strengthening of weak grain boundaries in the re-crystallized state. As a result the modified compacts exhibit superior surface resistance to low-energy deuteron irradiation. © 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2009.10.015

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In the macroscopic composition gradient (MCG) method, it is important to ensure that the MCG itself does not influence the phase transformation and microstructure behavior of the MCG alloy. The following two points should be theoretically and experimentally assessed to (1) ensure that the macroscopic composition profile is unchanged during aging at the lower temperature and (2) clarify the influence of the MCG on phase transformation, as it may influence microstructure formation even if the MCG profile does not change during aging. On the basis of experimental and theoretical investigations, 10 at. %/m is considered the maximum composition gradient which does not influence microstructure formation.

DOI： 10.1080/14786430903147114

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Publishing type：Research paper (scientific journal)   Publisher：Materials Science Forum  

A model for the nucleation and growth processes of Sn whisker is offered. High density of localized screw dislocations by deformation form the dense spiral steps of atomic scale on Sn surface. The spiral steps would induce the nucleation of Sn whisker. Edge dislocations localized at the same region where the dense screw dislocations exist supply Sn atoms to Sn whisker through pipe diffusion. Both screw and edge dislocations would bend along almost one direction, namely, to relax the external shear stress. The image force also helps to bend the dislocations perpendicular to the whisker side-surface. The bending of dislocations at root of whisker leads the bend of whisker. The pipe diffusion of Sn atoms through edge dislocations from bulk Sn toward whisker is suppressed at the bent part of edge dislocation, resulting in release of Sn atoms inside whisker and leading to the growth of whisker near its root. © (2010) Trans Tech Publications.

DOI： 10.4028/www.scientific.net/MSF.638-642.2688

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Precipitation behavior of a metastable β Ti alloy, Ti-6.8Mo-4.5Fe-1.5Al(masss%), during two-step aging has been investigated. Supersaturated β phase after solution treatment decomposes into β+ω phases during the first aging at 300°C for 2ks. β' phase is observed during the second aging at 500°C for 50s. It is suggested that reverse transformation of the ω phase to β phase during the second aging at 500°C for 50s gives rise to solute-lean and -rich regions in the β phase, and that β' phase is formed in the solute-rich region. β' phase being coherent with β phase has larger lattice parameter than β phase. β' phase acts as nucleation site for α phase, and accelerates the nucleation of α phase. © (2010) Trans Tech Publications.

DOI： 10.4028/www.scientific.net/MSF.638-642.461

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Corrosion resistance of anodized surfaces on high-purity magnesium (99.95 mass%), rolled sheets of ASTM AZ31B (Mg-2.9Al-0.85Zn) magnesium alloy and die-cast plates of ASTM AZ91D (Mg-9.1Al-0.75Zn) magnesium alloy has been studied. Anodization was conducted by environment-friendly electrolysis whose electrolyte consists of phosphate and ammonium salt. The anodized surface was covered with amorphous film, and showed only discoloration during salt spray test where formation of corrosion product (magnesium hydroxide) was well suppressed within 605 ks. Even when the anodized surfaces were trenched with ceramic knife to form locally exposed substrate, corrosion was well suppressed by formation of new type of dense protective films for each substrate which consist of oxygen, magnesium, aluminum and phosphorus. Anodic polarization curves indicate that the anodized surfaces show sacrificial function due to the thermodynamically unstable state of phosphorus in the anodized layers and its resulting release of electrons. From the viewpoint of kinetics in corrosion on the anodzed surfaces, the curves show that the anodized layers dissolve quite slowly into the electrolyte compared with the case of the untreated substrates. The excellent corrosion protection obtained by the anodization is considered to be based on the formation of a dense protective film on the exposed area, as well as sacrificial function of the amorphous anodized layer.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

W-(0.25-0.8)wt%TiC with equiaxed grain sizes of 50-200 nm and nearly full density of 99% was fabricated utilizing mechanical alloying (MA) in different gas atmospheres of H-2, Ar and N-2 and hot isostatic pressing. Microstructural and mechanical property examinations were conducted before and after irradiations with neutrons at 600 degrees C to 2 x 10(24) n/m(2) and 3 MeV He-ions at 550 degrees C to 2 x 10(23) He/m(2). It is found that TiC additions and MA atmospheres significantly affect grain refinement and baseline mechanical properties. The room-temperature fracture strength takes a maximum of 2 GPa for W-(0.25-0.5)%TiC with MA in H-2 (W-(0.25-0.5)TiC-H-2). At 1400-1700 degrees C superplastic behavior occurs for W-0.5TiC-H-2, but is suppressed for W-0.57TiC-Ar. No neutron irradiation hardening is recognized in W-0.5TiC-H-2 and W-0.5TiC-Ar. The critical fluence for surface exfoliation by He irradiation for W-0.3TiC-H-2 is more than 10 times as large as that for commercially available W materials. These results suggest that ultrafine grained W-TiC is capable of improved performance as the spallation neutron source solid target. (c) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2008.02.055

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Corrosion resistance of anodized surfaces on high-purity magnesium (99.95 mass%), rolled sheets of ASTM AZ31B (Mg-2.9Al-0.85Zn) magnesium alloy and die-cast plates of ASTM AZ91D (Mg-9.1Al-0.75Zn) magnesium alloy has been studied. Anodization was conducted by environment-friendly electrolysis whose electrolyte consists of phosphate and ammonium salt. The anodized surface was covered with amorphous film, and showed only discoloration during salt spray test where formation of corrosion product (magnesium hydroxide) was well suppressed within 605 ks. Even when the anodized surfaces were trenched with ceramic knife to form locally exposed substrate, corrosion was well suppressed by formation of new type of dense protective films for each substrate which consist of oxygen, magnesium, aluminum and phosphorus. Anodic polarization curves indicate that the anodized surfaces show sacrificial function due to the thermodynamically unstable state of phosphorus in the anodized layers and its resulting release of electrons. From the viewpoint of kinetics in corrosion on the anodzed surfaces, the curves show that the anodized layers dissolve quite slowly into the electrolyte compared with the case of the untreated substrates. The excellent corrosion protectivity obtained by the anodization is considered to be based on the formation of a dense protective film on the exposed area, as well as sacrificial function of the amorphous anodized layer.

DOI： 10.2320/matertrans.MC200718

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

In order to reveal the occurrence of superplasticity in ultra-fine grained W-TiC, W-0.5 wt. % TiC consolidates were fabricated utilizing mechanical alloying (MA) in purified H, (W-0.5TiC-H-2) or Ar (W-0.5TiC-Ar) and hot isostatic pressing. The W-0.5TiC-H-2 and W-0.5TiC-Ar feature equiaxed ultra-fine grains with average diameters of 150 and 70 nm, respectively, and W-0.5TiC-Ar contains a high density of nano-sized Ar bubbles. Tensile tests were conducted at 1673-1973 K (0.45-0.54T(m), T-m: melting point of W) at initial strain rates from 5 x 10(-5) to 5 x 10(-3) s(-1). It is found that W-0.5TiC-H-2 exhibits a large strain rate sensitivity of flow stress, m, of 0.5-0.6, which is a feature of superplastic materials, whereas W-0.5TiC-Ar exhibits a smaller m value of approximately 0.2. This suggests that the Ar bubbles cause an adverse effect on superplastic deformation. The activation energy for deformation is 300 kJ mol(-1) for W-0.5TiC-H-2 and 570 kJ mol(-1) for W-0.5TiC-Ar, corresponding to those for grain boundary diffusion and lattice diffusion in W, respectively. Each deformation controlling mechanism is discussed. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.msea.2007.05.009

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Finer intragranular bainite in steel welds has been known to be effective to improve strength and toughness greatly. The clTect of the starting temperature (B<inf>s</inf>) and the starting time (t<inf>s</inf>) of the nucleation of intragranular bainite on the formation and configuration of intragranular bainite arc examined by controlling the chemical compositions of Ni and B. It could be found that high concentration of Ni and low concentration of B induced high volume fraction of fine intragranular bainite. The results arc analyzed in terms of the BS and the t<inf>s</inf>.

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DOI： 10.1016/j.jnucmat.2008.12.183

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Microstructural evolution in a low cost beta titanium alloy, Ti-6.8Mo-4.5Fe-l.5Al, has been investigated especially in view of the initial microstructure before phase precipitation. During aging at 673 K., isothermal α phase is initially formed, and then a phase is formed at the isothermal ω phase which is a nucleation site. A large number density of athcrmal co phase, which is formed by quenching alter solution treatment at 1123 K, likely have an cffcct to accelerate a phase nucleation during aging at 773 K. compared with a specimen not quenched after the solution treatment. In a two-step aging, i.e., the solution treatment →573K for 2 ks-→773 K, the first aging yields formation of isothermal ω phase, and the sccond aging for a short time yields formation of phase and that for a further time yields formation of αphase. Acceleration of α phase formation in the two-step aging is attributable to the fact that β phase is a nucleation site for α phase. The formation β phase occurs in the β stabilizers enriched β phase due to compositional partitioning from ω phase.

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Microstnicturc formation during cooling from p phase in Ti-{15, 20) Nb-(0, 10, 20) Zr (ai%) alloys have been examined to reveal the effects of cooling rate and Zr addition on the microstructure formation. Specimens solution-treated at 1000°C in (5 phase field were qucnchcd in iccd brine (IBQ) or cooled in air (AC). Decrease of the cooling rate from IBQ to AC results in suppression of α phase formation in Ti-15Nb-(0, 10) Zr and Ti-20Nb alloys. Isothermal to phase formation in the AC specimens suppresses the formation of ω phase. Addition of 20at%Zr into Ti-(15, 20) Nb alloys suppresses formation of α phase in the IBQ specimens. Both cooling rate and Zr addition affect the competitive formation process of α and ω phases in Ti-(15, 20) Nb alloys during cooling front 1000°C.

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It is well known that formation of intragranular bainite (IGB) improves toughness of steels. The inclusions of oxide, sulfide, nitride, their complexes and so on act as nucleation sites for IGB. However, the inclusions act as the nucleation site for cleavage. Therefore, instead of inclusions, the stress field around small-angle dislocation boundary (SADB) has been examined whether it is effective or uot for the nucleation of IGB. It was confirmed that SADB acts effectively as nucleation sites for IGB, resulting in both the formation of finer IGB and the improvement of toughness.

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DOI： 10.1016/j.jnucmat.2008.12.187

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Mechanism of corrosion protection obtained by anodization for die-cast plates of ASTM AZ91D (Mg-9 mass%Al-0.7Zn) magnesium alloy has been studied. Anodization was conducted by conventional Dow17 which utilizes chromium oxide (VI), ammonium fluoride and phosphoric acid, and by environment-friendly Anomag whose electrolyte consists of phosphate and ammonium salt. The anodized surface obtained in Dow17 showed local corrosion in salt spray test (SST) after similar to 500ks to form corrosion product consisting of magnesium hydroxides. On the other hand, the surface anodized in Anomag was covered with amorphous film, showed only discoloring in SST and corrosion product was scarcely observed. When the anodized surfaces were trenched with ceramic knife to form locally exposed substrate, corrosion product was formed on the trench in the case of Dow17, but corrosion was well suppressed by formation of new type of protective film in the case of Anomag. Anodic polarization curves indicate that the surface anodized in Dow17 is protected by passive substances through which electrolyte can easily reach the substrate, and that in Anomag show sacrificial function where the anodized layer dissolves quite slowly into the electrolyte prior to the substrate. The excellent corrosion protectivity obtained in Anomag is considered to be based on the formation of a new type of protective film as well as sacrificial function of the original amorphous anodized layer.

DOI： 10.2320/matertrans.L-MRA2007881

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In order to examine the effects of 2 wt% Ti addition on microstructures and room- and high-temperature strengths for fine-grained, particle dispersed V-Y alloys, a V-1. 7Y-2. I Ti (in wt%) alloy was fabricated by powder metallurgical (P/M) methods. Microstructural examinations were made by transmission electron microscopy (TEM). Tensile tests were performed at temperatures from room-temperature to 1273 K at initial strain rates from I X 10(-5) to I X 10(-2) s(-1). The results were compared with those of V-(1.7-2.4)Y and V-4Cr-4Ti (NIFS heat-1) alloys. TEM examinations showed that 2.1% Ti addition provides an extended capability of maintaining a fine-grained structure in P/M V-Y alloys with larger interparticle distance. Tensile test results indicated that the high-temperature yield strength of V-1.7Y-2.1T is considerably higher than expected from the grain-size dependence of the yield strength, and that the deformation controlling mechanism is essentially the same as that for V-1.7Ti. The observed effects of Ti addition are discussed. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2007.03.071

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Effects of neutron irradiation on microstructural evolution and radiation hardening were examined for fine-grained W-0.3 wt%TiC (grain size of 0.9 mu m) and commercially available pure W (20 mu m). Both materials were neutron irradiated at 563 K to 9 x 10(23) n/m(2) (E &gt; 1 MeV) in the Japan Materials Testing Reactor (JMTR). Post-irradiation examinations showed that the microstructural changes and the degree of hardening due to irradiation were significantly reduced to fine-grained W-0.3TiCcompared with pure W, demonstrating the significance of grain refinement to improve radiation resistance. In order to develop ultra-fine grained W-TiC compacts with nearly full densification, the fabrication process was modified, so that W-(0.3-0.7)%TiC with 0.06-0.2 mu m grain size and 99% of relative density was fabricated. The achievable grain refinement depended on TiC content and milling atmosphere. The three-point bending fracture strength at room temperature for ultra-fine grained W-TiC compacts of powder milled in H, reached approximately 1.6-2 GPa for composition near 0.5%TiC. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnuemat.2007.04.008

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Ultra-fine grained (UFG) W-TiC with a high purity matrix of low dislocation density is expected to exhibit improve resistance to irradiation with neutrons and helium ions and the room temperature mechanical properties. Aiming at such UFG W-TiC with the desired microstructure, powders of W with 0.25-0.8 wt% TiC additions were subjected to mechanical alloying (MA) and hot isostatic pressing (HIP), where purified H-2 and Ar were used as the MA atmosphere. Microstructural observations and room- and high-temperature mechanical tests were performed for UFG W-TiC before and after neutron irradiation to a fluence of 2 x 10(24) nm(-2) at 873 K. It is shown that the MA atmosphere significantly affects grain refinement, room- temperature strength and high-temperature tensile plasticity of UFG W-TiC. W-0.5TiC with H-2 in MA (W-0.5TiC-H-2) shows a larger strain rate sensitivity of flow stress, m, of 0.5 similar to 0.6 at temperatures from 1673 to 1973 K, which is a feature of superplastic materials. Whereas W-0.5TiC-Ar shows a smaller m value of approximately 0.2. No radiation hardening is recognized in UFG W-0.5TiC-H-2 and W-0.5TiC-Ar.

DOI： 10.1088/0031-8949/2007/T128/015

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Publisher：The Japanese Society of Microscopy  

DOI： 10.11410/kenbikyo2004.42.198

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Language：English   Publishing type：Research paper (international conference proceedings)  

Ultra-fine grained (UFG) W-TiC with a high purity matrix of low dislocation density is expected to exhibit improve resistance to irradiation with neutrons and helium ions and the room temperature mechanical properties. Aiming at such UFG W-TiC with the desired microstructure, powders of W with 0.25-0.8 wt% TiC additions were subjected to mechanical alloying (MA) and hot isostatic pressing (HIP), where purified H2 and Ar were used as the MA atmosphere. Microstructural observations and room- and high-temperature mechanical tests were performed for UFG W-TiC before and after neutron irradiation to a fluence of 2×1024 n m-2 at 873 K. It is shown that the MA atmosphere significantly affects grain refinement, room-temperature strength and high-temperature tensile plasticity of UFG W-TiC. W-0.5TiC with H2 in MA (W-0.5TiC-H2) shows a larger strain rate sensitivity of flow stress, m, of 0.5∼0.6 at temperatures from 1673 to 1973 K, which is a feature of superplastic materials. Whereas W-0.5TiC-Ar shows a smaller m value of approximately 0.2. No radiation hardening is recognized in UFG W-0.5TiC-H2 and W-0.5TiC-Ar. © 2007 The Royal Swedish Academy of Sciences.

DOI： 10.1088/0031-8949/2007/T128/015

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

Microstructures of alkali- and/or heat-treated films on a Ti-15Zr-4Nb-4Ta alloy were analyzed by means of scanning electron microscopy, thin film X-ray diffraction and Auger electron spectroscopy. The cohesiveness of films was also evaluated by scratch tests. The films were formed by immersion in 5M aqueous NaOH solution at 60 degrees C for 86.4 ks (alkali treatment) followed by heating at 400-600 degrees C for 3.6 ks. The film on alloy formed by alkali treatment exhibits the same strucutre as that formed on an alkali-treated titanium. Compositional gradient of alloying elements, Zr, Nb and Ta, is detected in the film. The cohesion of alkali-treated film is considerably increased by the heat treatment, and the maximum cohesion is obtained by heating at 600 degrees C. The increase in cohesion of alkali-treated film by heat treatment is due to both the diffusion of Zr into film and the formation of sodium titanate on substrate.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

Intragranular bainite is known to be effective to develop toughness greatly in steels. Effects of aging below eutectoid temperature before austenitization, the deformation before solution treatment and the duration of solution treatment on nucleation of intragranular bainite have been examined. In the austenite (gamma) region where carbide pre-existed, the stress due to inverse transformation, ferrite (alpha) to gamma, would be introduced into fine austenitized region with lower transus temperature to gamma, resulting in the introduction of stable small-angle boundary at high temperatures acting as the nucleation site for intragranular bainite lath. Deformation of a by cold rolling before solution treatment enhances the nucleation of intragranular bainite, suggesting that the above gamma region through the inverse transformation is easily deformed by the hardened neighboring alpha. In the deformed gamma region, small-angle boundary would be more easily introduced, acting as nucleation site for intragranular bainite. Intragranular bainite lath grew and hardness decreased by prolonging the duration of solution treatment, indicating that transformation stress introduced by the pre-treatment was influenced by solution treatment. The effect of sulfur addition on formation of intragranular bainite was also analyzed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

Microstructure evolutions and hardness variation during aging in metastable beta titanium alloy TIMETAL (R) LCB have been examined. In as-quenched specimen after solution treatment, athermal omega phase formed. Isothermal omega phase formed during aging at 623 K, and alpha phase formed after precipitation of isothermal to phase during aging at 673 and 773 K. Alpha phase nucleated at isothermal omega phase, and had the orientation relationship with beta and omega, (111)(beta)//(0001)(omega)//(11 (2) over bar0)(alpha) and [10 (1) over bar](beta)[11 (2) over bar0](omega)//[0001](alpha). During aging at 873 K, alpha phase formed without isothermal omega phase. Hardness increased with increasing aging time and decreasing aging temperature, partly because number density of isothermal omega or alpha precipitates increased with increasing aging time and decreasing aging temperature.

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.45.839

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Effects of neutron irradiation were examined on microstructural evolution in powder metallurgically processed V-1.6Y (in wt%) alloys comprising essentially fine grains and very fine dispersoids of Y2O3 and YN. The alloys feature a highly pure matrix free from gaseous interstitials such as oxygen and nitrogen. Optical and transmission electron microscopy observations revealed that the martensite of a vanadium bet structure with a tetragonality (c/a) of 1.06 formed heterogeneously in some of the bee grains of V-1.6Y irradiated at 290 and 600 degrees C to 0.25 and 0.6 displacement per atom, respectively, but not in unirradiated V-1.6Y. The martensite had {101)(bct) habit planes parallel to {110}(bct) in the matrix and a high density of {101)(bct) microtwins as the lattice invariant shear strain. To the authors' knowledge, the emergence of martensite is the first to be observed for vanadium or its alloys in neutron irradiated states. The cause of the martensite formation is discussed. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2006.07.016

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Intragranular bainite (alpha), which consists of 24 variants formed at random, in steels has been investigated in order to develop both strength and toughness. The orientation relationship, {011}alpha//{111}gamma, &lt; 11 (1) over bar &gt;alpha//&lt; 10 (1) over bar &gt;gamma and &lt;(2) over bar1 (1) over bar &gt;alpha//&lt;(1) over bar2 (1) over bar &gt;gamma, between intragranular bainite and austenite (gamma) has been analyzed to be an important controlling factor for toughness. It could be suggested that the increase in the number density of nucleation site for lath of intragranular bainite increases in both strength and toughness of bainitic steels.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Intragranular bainite (α), which consists of 24 variants formed at random, in steels has been investigated in order to develop both strength and toughness. The orientation relationship, {011}α//{111}γ, 〈111̄〉α//〈101̄〉γ and 〈2̄11̄〉α//〈1̄21̄〉γ, between intragranular bainite and austenite (γ) has been analyzed to be an important controlling factor for toughness. It could be suggested that the increase in the number density of nucleation site for lath of intragranular bainite increases in both strength and toughness of bainitic steels. © 2006 The Japan Institute of Metals.

DOI： 10.2320/jinstmet.70.874

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The high temperature deformation behavior of a fine-grained and particle-dispersed V-2.3%Y-4%Ti-3%Mo (mass%) alloy was investigated. The alloy was fabricated by powder metallurgical methods utilizing mechanical alloying and hot isostatic pressing (HIP), followed by annealing at 1273 K for 3.6 ks. Tensile tests were performed at temperatures from 873 to 1273 K at initial strain rates from 2.5 x 10(-5) to 1.0 x 10(-1) s(-1). X-ray diffraction analyses show that the HIPed and annealed specimens contain a significant amount of (Y, Ti)(2)O-3 and small amounts of YN, Ti2O3 and TiO. Transmission electron microscopy observations show that the matrix contains approximately 3%Ti and 3%Mo in solution and that the average diameters of the matrix grains and dispersoids are about 620 and 42 nm, respectively. Tensile test results show that the yield stress depends strongly on test temperature and strain rate. From the dependence of the yield stress measured at 1073 and 1273 K on plastic strain rate, it is found that the dependence is divided into three regions with different deformation controlling mechanisms: a recovery controlling process of a long range internal stress field associated with dispersed particle (the high-strain-rate region), grain boundary sliding (the medium-strain-rate region) and presumably solute atmosphere dragging (the low-strain-rate region). Effects of 4%Ti addition on the microstructures and high temperature deformation behavior are discussed.

DOI： 10.2320/matertrans.47.2497

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Amorphous and crystallized calcium phosphate (Ca-P) coatings on Ti substrate have been investigated by X-ray photoelectron spectroscopy (XPS). The Ca-P coating on Ti substrate was performed by radio frequency magnetron sputtering of a sintered hydroxyapatite (HAp) target. As-sputtered Ca-P coating having 1.81 of Ca/P ratio was amorphous. Annealing the as-sputtered amorphous coating at 600 degrees C resulted in crystallized coating into HAp and tetracalcium phosphate (TTCP). The XPS profile of amorphous coating is almost the same as that of annealed coating. The XPS profile of oxygen in the amorphous coating shows that oxygen atom combines with both phosphorus and calcium atoms, indicating the amorphous coating contains fundamental chemical bonds of both HAp and TTCP.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Amorphous and crystallized calcium phosphate (Ca-P) coatings on Ti substrate have been investigated by X-ray photoelectron spectroscopy (XPS). The Ca-P coating on Ti substrate was performed by radio frequency magnetron sputtering of a sintered hydroxyapatite (HAp) target. As-sputtered Ca-P coating having 1.81 of Ca/P ratio was amorphous. Annealing the as-sputtered amorphous coating at 600°C resulted in crystallized coating into HAp and tetracalcium phosphate (TTCP). The XPS profile of amorphous coating is almost the same as that of annealed coating. The XPS profile of oxygen in the amorphous coating shows that oxygen atom combines with both phosphorus and calcium atoms, indicating the amorphous coating contains fundamental chemical bonds of both HAp and TTCP. © 2006 The Japan Institute of Metals.

DOI： 10.2320/jinstmet.70.330

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

Size of bainite lath is sub-micron, corresponding to that of ultra-fine grained steel. Bainite has Kurdjumov-Sachs (K-S) crystal orientation relationship with austenite, in spite of the ultra-fine grained steel having no crystal orientation relationship. Parallelism of slip systems between variants was examined using stereographic analysis. The stereographic analysis clarified that the fraction of parallelism of slip systems in variants of bainite is greater than that of grains in ultra-fine grained steel without crystal orientation relationship. It could be suggested that 24 variants of bainite laths formed at random (intragranular bainite) are preferable to develop mechanical properties, for example, elongation and/or toughness.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In order to improve the resistance to serious radiation embrittlement in refractory metals. a process for microstructural control is presented, with significance of controlling the Substance, size, number density and distribution of dispersed particles. The process is applied to vanadium. a metal of group VA. with ultra-fine grains and finely dispersed, thermally stable particles. It is shown that the developed V (1,6 -2,6)%Y alloys have grain sizes between 170 and 340 nm and particle (Y2O3 and YN) sizes between 13 and 25 nm and exhibit the following noted features: (1) The microstructure is stable against vacuum heating at 1573 K for 1 h. (2) The vanadium matrix is very low in Solute oxygen and nitrogen, which are responsible for environmental embrittlement of vanadium, (3) The alloys exhibit good tensile strength and elongation at low temperatures; approximately 1.5 times more strength and about 70% of the elongation compared with a V-4Cr-4Ti (Nifs-Heat-1) alloy. (4) The developed alloys show good resistance to neutron irradiation at 563 K to 0.25 dpa and 873 K to 0.60 dpa. These fabrication processes and noted features are applicable to other group VA metals such as tantalum. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2004.12.017

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The cohesiveness of films on titanium was evaluated by a scratch test. The films were formed on titanium by immersion in an aqueous solution of NaOH (hereafter referred as "alkali-treated") followed by heating at 500-700 degrees C for 3.6 ks. The cohesion of the alkali-treated film was increased by the heat treatment. and the maximum cohesion was obtained by heating at 500 degrees C. The film on alkali and heat-treated titanium consisted of both microporous films and dense films. The microporous film furthest from the titanium surface was barely cohesive, whereas the dense film showed cohesion with titanium. The cohesion of film formed by alkali-treatment was increased on heating, but the formation of TiO2 (rutile) at the film-titanium interface on heating at and above 600 degrees C caused a deterioration in the cohesion.

DOI： 10.2320/matertrans.46.207

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.44.991

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DOI： 10.2355/tetsutohagane1955.91.12_882

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.44.981

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.43.1041

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.43.766

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Other Link： https://jlc.jst.go.jp/DN/JALC/00376941280?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

Tensile deformation behavior at an early stage in a bainitic steel has been examined by detecting formation of surface relief, and analyzed stereographically. The variants of bainite could be identified by both morphology and crystallography. The surface relief was detected in a bainite-variant at an early stage of deformation. It could be analyzed that the variant with surface relief has many slip systems of larger Schmid factors compared with those that other variants have, resulting in the early stage of deformation of bainite being largely dependent on Schmid factor.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In order to examine the high temperature strength of fine-grained, particle-dispersed V-Y alloys as a function of grain size and dispersed particle density, three V-(1.7-2.4)Y (in wt%) alloys were prepared by mechanical alloying and hot isostatic pressing. The alloys had grain sizes of 270-500 nm, particle size of around 15 nm and particle densities of (1.3-7.2) x 10(21) m(-3). The alloys, together with V-4Cr-4Ti (NIFS-Heat1), were annealed and tensile tested at room and high temperatures from 873 to 1273 K. At room temperature and up to around 1073 K, V-(1.7-2.4)Y alloys exhibited higher strengths than V-4Cr-4Ti, with strength increasing with decreasing grain size and increasing particle density. Above 1173 K, however, V-(1.7-2.4)Y alloys showed lower strengths than V-4Cr-4Ti. These results are due to a strong temperature dependence of strengths of V-(1.7-2.4)Y above 923 K compared with that of V-4Cr-4Ti. The observed mechanical behavior of V-(1.7-2.4)Y is discussed from the viewpoint of the deformation controlling mechanism. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2004.04.308

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Effects of neutron irradiation on the microstructure and hardness in V-1.6 and 2.6Y (mass%) alloys were studied. The alloys consisted of both fine grains of a few hundreds of nanometers in diameter with finely dispersed particles and small amounts of coarse grains of a few micrometers in diameter without dispersed particles. The microstructures after neutron irradiation at 290 and 800degreesC to 0.25 and 0.7 dpa, respectively, were examined with transmission electron microscopy. Irradiation did not change the grain size. Interstitial loops and voids were formed in the coarse grains irradiated at 290degreesC, while voids were formed only in the fine grains. The number density of voids decreased with decreasing grain size. Interstitial loops and voids were not observed in V-1.6Y alloy irradiated at 800degreesC, while thin plates were formed only in the coarse grains. The formation of interstitial loops and voids was efficiently suppressed in the fine grains. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jnucmat.2004.04.091

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Decomposition processes of beta phase in a Ti-15Zr-4Nb-4Ta alloy during isothermal holding have been examined mainly by transmission electron microscopy. Specimens solution-treated at 1000degreesC in beta phase field were held at temperatures between 400 and 600degreesC. alpha phase lath formed in beta phase during isothermal holding at 600degreesC. After holding at 600degreesC for a short duration, remaining beta phase, untransformed beta phase into a phase at 600degreesC, was transformed into alpha' martensite during quenching into ice-brine. As increasing holding time at 600 C, remaining,B phase was transformed into alpha" or athermal omega phases during quenching. After prolonged holding at 600degreesC, remaining beta phase was not transformed during quenching. Enrichment of Nb, Ta and Zr into remaining phase occurred with increasing holding time at 600degreesC, resulting in the variation of transformation of remaining beta phase during quenching. Microstructures evolved at 400 and 500degreesC were almost same as those at 600degreesC.

DOI： 10.2320/matertrans.45.1624

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

Dispersion of fine proeutectoid ferrite and/or enhancement of formation of intragranular bainite have been performed to improve mechanical properties at/around welded region in steels. In the present study, effects of Ti-based oxide inclusions on the nucleation and growth processes of proeutectoid ferrite and bainite are examined in terms of the number density and size of the inclusions in steels with different gamma-grain sizes. Ti-oxide acts as effective nucleation site of granular proeutectoid ferrite and bainite. Especially, it could be suggested that fine inclusions induce nucleation of high density of intragranular bainite. On the other hand, growth of (Ti, Mn)-oxide on grain boundary enhances both the depletion of Mn at/around grain boundary and formations of elongated procutectoid ferrite along grain boundary, Widmanstatten ferrite and aggregate of nearly single-variant of bainite at grain boundaries. The Mn depletion could form the three kinds of ferrites mentioned above, remarkably, at grain boundaries, resulting in the suppression of formation of intragranular bainite.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

An alloy having ultra-fine grains with dispersed particles is expected to have the resistance of irradiation embrittlement. We examine the microstructures of V-1.6 and 2.6Y alloys, having ultra-fine grains with dispersed particles, after neutron irradiation at temperatures between 290 and 800degreesC. The grain size was the level of a few hundreds of nanometers, and the size in diameter of V-2.6Y alloy was much smaller than that of V-1.6Y alloy, where the irradiation did not change the size. The number density of particles in V-2.6Y alloy was higher than that in V-1.6Y alloy. Voids were formed only at 290degreesC, where the number density of voids in V-2.6Y alloy was smaller than that in V-1.6Y alloy. The void formation was efficiently suppressed due to fine-grains and dispersed particles.

DOI： 10.2320/matertrans.45.29

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DOI： 10.2355/tetsutohagane1955.90.8_574

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DOI： 10.2355/tetsutohagane1955.90.3_141

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TRANS TECH PUBLICATIONS LTD  

Microstructures of the interface between plasma-spray coated hydroxyapatite (HAp) and Ti-alloy substrate have been investigated mainly by means of transmission electron microscopy. The results obtained are as follows; HAp coating exhibits a high crystallinity. The interface of HAp/Ti-alloy is winding at an interval of about 100 mum and thickness of HAp coating is about 50 mum. Al2O3 abrasives remained in both HAp coating and Ti-alloy substrate around the interface. Amorphous phase was not observed at the interface. The grain size of Ti-alloy in the vicinity of the interface is about 10 to 100nm in diameter, while that far from the interface is about 3 mum in diameter. Miniaturization of Ti-alloy grain around the interface was occurred by plasma spraying. There is no specific crystallographical orientation relationship between HAp and Ti-alloy at the interface, indicating bonding of the interface is essentially mechanical one such as an anchor effect.

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.42.871

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Language：Japanese   Publishing type：Research paper (other academic)  

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Language：Japanese   Publisher：コンパス社  

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DOI： 10.2355/tetsutohagane1955.89.3_342

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

Phase decomposition in a Ti-13 mass%Nb-13 mass%Zr alloy during isothermal aging at 600 C has been investigated by means of transmission electron microscopy and Vickers hardness measurements. Specimens solution-treated at 1000 C in phase field were quenched and aged at 600degreesC in (alpha + beta) region. Beta phase was fully transformed into martensitic alpha' laths by quenching from 1000degreesC. Formation of beta phase on tempered alpha' lath interfaces occurred during aging. Early in the stage of aging, beta phase transformed into alpha" martensite completely by quenching. As increasing in aging time, athermal omega phase was formed in beta phase by quenching. Beta phase was stabilized by prolonged aging. Enrichment of Nb content into beta phase occurred with increasing in aging time, resulting in the formations of athermal omega phase and (alpha + beta) two-phase structure. The hardness increased with the m phase formation in beta phase, followed by the decrease of hardness due to suppression of omega phase formation induced by enrichment of Nb in beta phase.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The effects of excess Mg and Si contents on the isothermal ageing processes of Al-Mg2Si alloys have been investigated by means of transmission electron microscopy and the following results were obtained. After the formation of beta" needles inducing large age hardening, cuboid beta particles precipitate in both the excess Mg and the quasi-binary alloys, but fine Si particles nucleate in the excess Si alloys. In the quasi-binary alloy, the following reaction is the precipitation of beta' rods and then beta plates form. In the excess Si alloys, various rodlike precipitates form after the precipitation of beta" needles and Si particles in the sequence: Type-A rods--&gt;Type-B rods --&gt; beta' rods. This precipitation sequence can be understood by considering the chemical compositions of them determined by Matsuda et al.

DOI： 10.2320/matertrans.43.1371

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Language：English   Publisher：The Iron and Steel Institute of Japan  

The effects of boron addition on the tempering processes of 0.1C-9Cr martensite have been studied. The alloys with and without 98ppm boron were prepared. The specimens austenitized at 1200ºC for 1.2ks were quenched into iced brine. The structure was consisted of α' martensite laths. They were heated at 10ºC/min to 900ºC. Temperature derivative of electric resistivity, dρ/d<i>T</i>, exhibited small increase at temperature around 740°C (reaction A), gradual decrease at temperatures between 750°C and 800°C (reaction B), large decrease at around 815°C (reaction C) and small increase at around 830°C (reaction D). Transmission electron microscopic observations showed that the reactions in the alloy with boron were related to the dissolution of cementite, the precipitation of M<SUB>23</SUB>(B·C)<SUB>6</SUB> and M<SUB>7</SUB>(B·C)<SUB>3</SUB>, the austenite formation, and the dissolving of the carbides with further increase of austenite, respectively. In the alloy without boron, they corresponded to the dissolution of cementite, the precipitation of M<SUB>7</SUB>C<SUB>3</SUB>, the austenite formation, and the dissolving of M<SUB>7</SUB>C<SUB>3</SUB> with further increase of austenite, respectively. The boron addition to Fe-lowC-highCr alloy promotes M<SUB>23</SUB>(B·C)<SUB>6</SUB> formation and retards the α→γ transformation.

DOI： 10.2355/isijinternational.42.Suppl_S72

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The exothermic reaction occurring after beta" precipitation in Al-Mg-Si alloys has been investigated by means of differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The reaction peak height observed in DSC increases with increasing excess Mg or decreasing excess Si content from Al-Mg2Si quasi-binary composition. It was confirmed that this reaction peak arises from the precipitation of cuboid beta-Mg2Si particles related to the matrix with the cube-cube orientation relationship. At the later stage of ageing, thin beta-Mg2Si plates nucleate at the cuboid beta-phase particles. The orientation relationship of them is rotated 45degrees or 18.4degrees in the further aged specimens about the direction normal to the {001}(Al) parallel to {001}(beta) habit plane from the cube-cube relationship. The changes in morphology and the crystallography of the beta-Mg2Si precipitates with the progress of ageing can be explained qualitatively in terms of coherency and interface energy of the precipitates.

DOI： 10.2320/matertrans.42.2576

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

The phase transformations in a Ti-10 mass%Zr alloy during continuous cooling and isothermal holding have been investigated mainly by means of hot stage optical microscopy. During cooling from beta phase at 100 degreesC/s, alpha' plates formed martensitically at temperatures around 180 degreesC together with sharp and coarse surface reliefs. The Widmanstatten alpha laths mostly nucleated directly on a beta phase grain boundary and grew into one of the grains during isothermal holding at temperatures between 650 and 850 degreesC. At beta grain boundaries, alpha allotriomorphs often nucleated and Widmanstatten alpha laths grew from them during isothermal holding at 800 degreesC. Widmanstatten alpha plates exhibited sharp surface reliefs. The precipitation of alpha phase exhibited the C-curve with the nose at around 775 degreesC. The Ms temperature so far reported to be similar to 805 degreesC is not the martensite start temperature but the nose temperature for Widmanstatten ce laths.

DOI： 10.2320/matertrans.42.2398

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Effects of omega phase precipitation on beta --&gt; alpha, alpha" transformations in a metastable beta titanium alloy have been studied by means of transmission electron microscopy. Isothermal holding at 300 degreesC for 100 min after the solution-treatment at 1000 degreesC yielded homogeneously distributed spherical omega phase particles of similar to 10 nm in diameter. With raising the holding temperature, omega phase particles of the same orientation variant precipitated as groups. At temperatures above 350 degreesC, alpha phase laths nucleated at the omega/beta interfaces and grew into both the matrix and omega particles with consuming omega phase particles. Thus, the alpha/omega Takemoto and the omega/beta Burgers relationships were held simultaneously, and the orientation of or laths nucleating at an omega/beta interface was determined uniquely. In the specimens quenched directly from beta single-phase region, alpha" martensite plates nucleated preferentially at beta grain boundaries. The alpha" formation, however, was accelerated by a short time holding at temperatures between 600 and 300 degreesC, but was largely retarded by the progress of omega phase precipitation. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-5093(00)01891-8

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN INST METALS  

Phase transformations from bcc beta to hcp alpha in a Ti-10wt%Zr alloy during continuous cooling and isothermal holding have been studied. The solution-treated specimens at 1000degreesC for 600s were continuously cooled at 1-100degreesC/s in hot stage optical microscope. During the cooling at 1degreesC/s, fine but not sharp surface reliefs were observed to form at temperatures below 550degreesC. On the other hand, in the specimen cooled at 100degreesC/s sharp surface reliefs appeared and increased in number at temperatures below 180degreesC. Transmission electron microscopy for these specimens after cooling to room temperature revealed that the density of highly dislocated alpha'-laths decreased in number and almost dislocation-free alpha-laths increased with reducing the cooling rate. In the isothermally decomposed specimens, the Widmanstatten alpha formed at grain boundary and grew into the matrix grains. The precipitation curve of alpha-laths at temperatures between 650 and 850degreesC shows C-curve indicating a diffusional transformation occurred even under Ms temperature (805degreesC) so far reported.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN INST METALS  

The effects of B addition on the decomposition of 0.1C-9Cr austenite have been studied. The alloys with and without 98ppm B were prepared. The specimens austenitized at 1200degreesC for 1.2ks were isothermally transformed at temperatures 620-750degreesC. The microstructures formed were examined by means of optical and transmission electron microscopies. The precipitation curves for primary ferrite in the steels show C-curves with the noses at temperatures about 720degreesC. The addition of 98ppm B accelerated the ferrite formation. Transmission electron microscopy revealed that M-23(B,C)(6) particles precipitated at prior austenite grain boundaries in the very early stage of decomposition in the B containing alloy and acted as potent nucleation sites for ferrite grams. These ferrite particles grew into the austenite grain with a repeated nucleation of M-23(B,C)(6) particles. In the B free alloy, M23C6 Particles played the roll similar to M-23(B,C)(6) Particles at the moving ferrite interfaces but the formation Of M23C6 particles was significantly slow.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN INST METALS  

Processes of Mo grain growth and carbide formation during hot isostatic pressing (HIP) in Mo-HfC composite materials prepared by mechanical alloying (MA) method have been investigated by optical and transmission electron microscopies. The Mo grain growth during HIP is suppressed by the precipitation of (Mo,Hf)(2) C, and by increasing MA duration. The precipitation of (Mo,Hf)(2)C particles depends on the grain boundary diffusion of Hf. Alpha-Mo2C particles are also formed within a grain homogeneously by rapid diffusion of carbon.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN INST METALS  

Phase equilibria at 1523 K and the phase decomposition processes during continuous cooling at various rates from 1523 K in a Ti-4Sat%Al-10at%Zr alloy have been investigated in view of morphology and crystallography of microstructures. Two phases, alpha and beta, are in equilibria at 1523 K. During cooling, alpha phase is ordered to alpha(2) phase, and gamma plates nucleate at alpha(2) grain boundaries and grow with inheriting antiphase domain boundaries in the alpha(2) matrix with sharp surface reliefs. resulting in the formation of lamellar structure. The beta phase is ordered to B2 structure during cooling. The omega phase of B8(2) structure forms in the B2 phase, and acts as nucleation sites for alpha(2) Widmanstatten structure. As decreasing cooling rate, in-situ nucleation of gamma phase in the alpha(2) Widmanstatten structure occurs also with inheriting the antiphase domain boundaries of the alpha(2) Widmanstatten structure..

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.39.970

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN INST METALS  

Phase transformations in the temperature range from 350 to 600 degrees C in a duplex stainless steel have been investigated by means of differential scanning calorimetry (DSC), electron resistivity measurement (ERM) and transmission electron microscopy (TEM). The solution treated specimens were either heated continuously at a constant rate or aged isothermally. During the continuous heating up to 650 degrees C, the compositional fluctuation, the homogeneous precipitation of fine plates and the dissolution of them occurred at temperatures around 400, 450 and 500 degrees C, respectively. In the isothermally aged samples, the compositional fluctuation, the formation of the plate-shaped precipitates and the precipitation of fine spherical Cu particles were observed at temperatures under 400, between 400 and 550, and between 550 and 600 degrees C, respectively. The precipitation of austenite plates was recognized above 600 degrees C.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Minerals, Metals &amp; Materials Soc (TMS)  

The critical minimum size of stable precipitate in the vicinity of the edge of miscibility gap is experimentally determined for Ni3Al precipitate particles in the Ni-Al and Cu4Ti particles in the Cu-Ti binary alloy systems using the macroscopic composition gradient method recently proposed. The results obtained are as follows: the critical nucleus size shows a rapid increase to several tens of nanometers in a very narrow composition region less than 0.3 at. pct from the phase boundary. Such a big critical size of the nucleus is statistically rationalized by the conventional nucleation theories, but remains kinetically unreasonable.

DOI： 10.1007/s11661-999-0115-8

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Language：Japanese   Publisher：The Japan Institute of Metals and Materials  

DOI： 10.2320/materia.37.365

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A new characterization method of the microstructure utilizing the macroscopic compositionally gradient alloy was recently proposed by the present authors. The influence of macroscopic composition gradient on the formation of a microstructure is estimated either theoretically or experimentally in the present paper. The results obtained are as follows: The theoretical investigation shows that the macroscopic composition gradient up to 10 at% per μm dose not give any influence on the formation of microstructure. The experimental examinations on the microstructural formation performed for the compositionally gradient alloy of 8.9 at% per 1 μm and the compositionally homogeneous specimen do not exhibit any difference in both microstructures.

DOI： 10.2320/jinstmet1952.62.7_648

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

A new experimental method to determine the phase boundary and phase equilibria is accomplished by using the transmission electron microscopic observation of alloys having the macroscopic composition gradient. The various phase boundaries, i.e., the coherent binodal and spinodal lines and incoherent binodal line, are distinctly determined for the Cu-Ti alloy system. Furthermore, the equilibrium compositions at the interface of precipitate/matrix are experimentally obtained for various particle sizes, and therefore, the Gibbs-Thomson relation is verified. It is expected that the composition gradient method proposed in the present study will become an important experimental method for microstructural characterization.

DOI： 10.1007/BF02649762

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The composition gradient method recently proposed is applied to determine the coherent phase boundaries of the Ni-V and Ni-Mo alloy systems by utilizing the alloys having the macroscopic composition gradient. The result, obtained are as follows: (1) The coherent phase boundaries of Ni/(Ni+ Ni3V) were experimentally determined to be a line connecting 15.5 at%V at 873 K and 18.0 at%V at 1173 K, which was consistent with Moreen's empirical results obtained from the metallographic examinations. (2) The phase boundaries of Ni/(Ni+Ni4Mo) and (Ni+Ni4Mo)/Ni4Mo were also obtained, which were almost coincident with those in the equilibrium phase diagram of Ni-Mo proposed by Massalski. The new method is recognized to be very powerful for a metallographic determination of the coherent phase boundary.

DOI： 10.2320/jinstmet1952.60.1_22

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：軽金属学会  

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&lt;b&gt;目的&lt;/b&gt; 近年、マウスにビタミン E を過剰摂取させると破骨細胞の巨大化を伴いつつ活性化することで骨吸収を促進し、骨粗鬆症を誘発する危険性があると報告された。しかし、骨芽細胞に与えるビタミンEの影響に関する詳細な検討はなされていない。そこで本研究では、ビタミンEで骨芽細胞を刺激することで、骨芽細胞自身ならびに破骨細胞活性化メカニズムにどのような影響を与えるのかについて検討した。&lt;br&gt;&lt;b&gt;方法&lt;/b&gt; マウス頭蓋冠由来骨芽細胞 MC3T3-E1 を、ビタミン E の主成分である&amp;alpha;-tocopherol(&amp;alpha;-toc)で刺激し、細胞増殖に与える影響を検討した。また、骨芽細胞から産生される破骨細胞活性化因子である IL-6 および IL-1&amp;beta;の量を ELISA 法で測定した。&lt;br&gt;&lt;b&gt;結果および考察&lt;/b&gt; MC3T3-E1 に&amp;alpha;-toc を作用させたところ、濃度依存的に細胞増殖が抑制され、継続的な&amp;alpha;-toc 刺激により、その効果は維持された。また、骨芽細胞 1 個あたりの IL-6 および IL-1&amp;beta;生産性を評価した結果、&amp;alpha;-toc 濃度依存的に高値を示した。さらに、&amp;alpha;-toc(50&amp;mu;M)刺激によって MC3T3-E1 の付着ならびに増殖時に認められる細胞突起の伸展が顕著に抑制された。したがって、&amp;alpha;-toc は骨芽細胞の増殖を抑制しつつ、骨芽細胞からの破骨細胞活性化因子の生産性を促進することで破骨細胞の活性化を誘導し、骨粗鬆症の発症を誘起しているのではないかと推察された。

DOI： 10.11428/kasei.68.0_283

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Language：Japanese   Publisher：JAPAN WELDING SOCIETY  

The new welding method called as F-MAG, which has been developed based on CO2 gas-shielded arc welding method (MAG) increase deposition rate of weld metal. F-MAG welding method is combined with hot-wire, as having been used in TIG arc- and laser-welding methods. F-MAG is performed using hot-wire which is inserted into the rear part of weld pool made with leading electrode. Hot-wire melts by both electrical heating of itself and heat of weld pool. Multi-layered weld metals were prepared using F-MAG and MAG. Microstructures and mechanical properties of both as-weld and reheated zones in uppermost layer of the multi-layered weld metals formed with F-MAG and MAG were examined and the effects of hot-wire on microstructures and mechanical properties were analyzed. Both the as-weld and reheated zones of weld metal formed with F-MAG consisted of acicular ferrite (AF), equiaxed ferrite and so on. Both strength and elongation in as-weld and reheated zones formed with F-MAG were superior compared with those formed with MAG. It could be suggested that strength increased by refinement of AF due to increase in the concentration of alloying elements being contained in hot-wire. Larger elongation of weld metal in F-MAG compared with that in MAG could be analyzed in terms of the Aggregate of acicular ferrite Laths with nearly Parallel Slip systems between neighboring acicular ferrite laths (ALPS). The number of AFs contained in an ALPS formed with F-MAG is larger than that with MAG, in spite of the sizes of ALPSs formed with MAG and F-MAG being almost same. Deformation occurs over a lot of AFs in the case of finer AF formed with F-MAG through the rotation of tensile test piece during deformation, resulting in the larger elongation.

DOI： 10.2207/qjjws.31.104

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Formations of Cu-rich precipitate in 18%Cr-1.5%Cu stainless steels without and with 0.5%Nb have been examined mainly using transmission electron microscopy. The specimens solution-treated at 1250°C were isothermally transformed at various temperatures between 500 and 850°C. Fine spherical Cu-rich solute zones were nucleated in the steels in the beginning of aging. These Cu-rich zones exhibited bcc structure and then transformed into 9R structure with twins during aging. The spherical 9R-Cu particles changed into rod-shaped fcc-Cu particles after prolonged aging. Laves phase of Fe 2Nb type started to form in the Nb-added steel almost after finishing nucleation and growth of Cu particles. Addition of Nb in the steel delayed the nucleation of the Cu-rich zones due to slow diffusion of Nb atoms in ferrite. © 2011 ISIJ.

DOI： 10.2355/isijinternational.51.657

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Bainite lath nucleated WithIN Grain (BWING) has been clarified to be greatly effective for the increase in both strength and toughness. The nucleation of BWING has been enhanced by the introduction of inclusion into austenite, which would act as nucleation site for BWING. However, the inclusion itself would be brittle and at the interface between inclusion and matrix, high density of dislocations are apt to be accumulated under deformation, inducing cleavage at the interface. As density of inclusion increases, steel would be strengthened, but brittle. Therefore, the introduction of dislocation network, that is, Small-Angle Dislocation Network (SADN) into austenite is tried in the present work. SADN would be stable in the high temperature region such as in austenite, because pinned dislocation existed in SADN would prevent the bow-out of dislocations through absorbing point defects. The formation of SADN in austenite, which act as nucleation site for BWING, was clarified experimentally. The bainite lath neighbor to the nucleated one might be formed under relaxing the stress field around the nucleated one and/or inclusion. It was analyzed that the average size of Aggregates of bainite Laths having nearly Parallel Slip systems between neighboring bainite laths (ALPS) corresponds to that of dimples on fracture surface. The process for ductile fracture is offered based on the crystallographic analysis using transmission electron microscopy. © 2011 ISIJ.

DOI： 10.2355/isijinternational.51.274

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