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-phase in Al-Mg-Si alloys during aging treatmentAhmed, A.*; Uttarasak, K.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Toda, Hiroyuki*; Yamaguchi, Masatake; et al.
Journal of Alloys and Compounds, 988, p.174234_1 - 174234_9, 2024/06
This study aims to clarify the growth process of the-phase in Al-Mg-Si alloys from the point of view of morphology evolution. For this research, the -phase orientation relationship, shape, growth process, misfit value, and interfacial condition between the -phase and Al matrix were investigated using high-resolution transmission electron microscopy (HR-TEM), focus ion beam (FIB), and optical microscope (OM). Results include the identification of {111} facets at the edges of the -phase, as well as the proposal of two new three-dimensional shapes for the -phase. We purposed the morphology evolution during the growth process of Mg
Si crystal and calculated the misfit to understand the unstable (111) facet has a higher misfit value as compared to the (001) and (011) facets. Our observations provide how they influence the behavior of MgSi crystals.
MnShimizu, Kazuyuki*; Nishimura, Katsuhiko*; Matsuda, Kenji*; Akamaru, Satoshi*; Nunomura, Norio*; Namiki, Takahiro*; Tsuchiya, Taiki*; Lee, S.*; Higemoto, Wataru; Tsuru, Tomohito; et al.
Scripta Materialia, 245, p.116051_1 - 116051_6, 2024/05
Times Cited Count：0Hydrogen at the mass ppm level causes hydrogen embrittlement in metallic materials, but it is extremely difficult to experimentally elucidate the hydrogen trapping sites. We have taken advantage of the fact that positive muons can act as light isotopes of hydrogen to study the trapping state of hydrogen in matter. Zero-field muon spin relaxation experiments and the density functional theory (DFT) calculations for hydrogen trapping energy are carried out for AlMn. The DFT calculations for hydrogen in AlMn have found four possible trapping sites in which the hydrogen trapping energies are 0.168 (site 1), 0.312 (site 2), 0.364 (site 3), and 0.495 (site 4) in the unit of eV/atom. Temperature variations of the deduced dipole field width (
) indicated step-like changes at temperatures, 94, 193, and 236 K. Considering their site densities, the observed change temperatures are interpreted by trapping muons at sites 1, 3, and 4.
Bendo, A.*; Matsuda, Kenji*; Nishimura, Katsuhiko*; Nunomura, Norio*; Tsuchiya, Taiki*; Lee, S.*; Marioara, C. D.*; Tsuru, Tomohito; Yamaguchi, Masatake; Shimizu, Kazuyuki*; et al.
Materials Science and Technology, 36(15), p.1621 - 1627, 2020/09
Times Cited Count：8 Percentile：46.23(Materials Science, Multidisciplinary)Metastable phases in aluminum alloys are the primary nano-scale precipitates which have the biggest contribution to the increase in the tangible mechanical properties. The continuous increase in hardness in the 7xxx aluminum alloys is associated with the phase transformation from clusters or GP-zones to the metastable 
phase. The transformation which is structural and compositional should occur following the path of the lowest activation energy. This work is an attempt to gain insight into how the structural transformation may occur based on the shortest route of diffusion for the eventual structure to result in that of phase. However, for the compositional transformation to occur, the proposed mechanism may not stand, since it is a prerequisite for the atoms to be at very precise positions in the aluminum lattice, at the very beginning of structural transformation, which may completely differ from that of the GP-zones atomic arrangements.
hydrogen partitioning controlToda, Hiroyuki*; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Su, H.*; Fujihara, Hiro*; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito; et al.
Tetsu To Hagane, 105(2), p.240 - 253, 2019/02
Times Cited Count：0 Percentile：0(Metallurgy & Metallurgical Engineering)no abstracts in English
Tsuchiya, Terumitsu*; Narita, Norifumi*; Tani, Kazuyuki*
JNC TJ7400 2005-022, 45 Pages, 2004/01
no abstracts in English
Kawamura, Hiroshi; Ishitsuka, Etsuo; Tsuchiya, Kunihiko; Nakamichi, Masaru; Uchida, Munenori*; Yamada, Hirokazu*; Nakamura, Kazuyuki; Ito, Haruhiko; Nakazawa, Tetsuya; Takahashi, Heishichiro*; et al.
Nuclear Fusion, 43(8), p.675 - 680, 2003/08
Times Cited Count：28 Percentile：63.92(Physics, Fluids & Plasmas)no abstracts in English
Yamaoka, Hiroto*; Tsuchiya, Kazuyuki*; Awano, Toshihiko*; Oka, Kiyoshi
Ishikawajima Harima Giho, 42(5), p.260 - 264, 2002/09
no abstracts in English
*; Saido, Masahiro; Nakamura, Kazuyuki; Akiba, Masato; ; Goto, Yoshitaka*; *; *; Yamaki, Takahiro*; *; et al.
Journal of Nuclear Materials, 233-237(PT.A), p.781 - 786, 1996/00
Times Cited Count：13 Percentile：72.37(Materials Science, Multidisciplinary)no abstracts in English
Yamashita, Shinichiro; Abe, Hiroaki*; Sato, Daiki*; Owaki, Masao*; Sakamoto, Kan*; Kusagaya, Kazuyuki*; Tsuchiya, Akiyuki*
no journal, ,
The ATF Working Group (ATF-WG), which started its activities in July 2017, has been considering safety requirements for the introduction of ATF while incorporating overseas knowledge of the United States, which is ahead of ATF development. In the ATF-WG activities, based on the safety design of the core and fuel of LWRs for power generation, we organized the concept of extracting the evaluation items necessary for ATF safety design and the importance of ATF safety. The way of thinking organized here can also be used for the research and development of ATF that are currently underway, and we are going to summarize it in a report in the future.
