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Moriyama, Junichiro*; Takakuwa, Osamu*; Yamaguchi, Masatake; Ogawa, Yuhei*; Tsuzaki, Kaneaki*
Computational Materials Science, 232, p.112650_1 - 112650_11, 2024/01
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)The present study focuses on a novel hydrogen-improved strength-ductility balance in some practical Fe-Cr-Ni-based austenitic alloys, which directly depends on the solute hydrogen content. The hydrogen absorption energy of the Fe-Cr-Ni model alloys with the face-centered cubic structure was examined using first-principles calculations to verify the contribution of Cr and Ni substitutions from Fe to the hydrogen solubility in the alloys. The Cr substitution substantially reduced the hydrogen absorption energy compared to the Ni substitution, whereby the increased Cr/Ni ratio exerts higher hydrogen solubility. The propensity in the calculations coincided with the experimental results obtained previously in the practical alloys with various Cr / Ni ratios.
Oku, Takayuki; Yamada, Satoru; Sasao, Hajime*; Suzuki, Junichi; Shinohara, Takenao*; Hirota, Katsuya*; Ikeda, Kazuaki*; Tsuzaki, Tsuyoshi*; Kiyanagi, Yoshiaki*; Furusaka, Michihiro*; et al.
Physica B; Condensed Matter, 385-386(2), p.1225 - 1228, 2006/11
Times Cited Count：10 Percentile：44.47(Physics, Condensed Matter)We have developed a magnetic neutron lens based on an extended Halbach-type permanent sextupole magnet with magnet pieces of NEOMAX-44H, -35EH and high saturation magnetization material, permendule. The aperture size of the magnet is 35 mm in diameter and the magnet length is 2,400 mm. The magnet generates a sextupole magnetic field 
with a gradient coefficient 
=10,600 T/m
inside the aperture, where 
is a distance from the magnet center axis. To prevent neutrons from hitting and reflecting at the inner surface of the magnet, the surface is covered with cadmium (Cd) sheets and also Cd pinhole slits with size of 30 mm in diameter are positioned in series inside the magnet aperture, resulting in the effective diameter of 30 mm. The neutron focusing property of the magnet is investigated by using pulsed polarized neutrons. The obtained results are discussed with the precise simulation results. Its application to the focusing-geometry small-angle neutron scattering experiments is also discussed.
Moriyama, Junichiro*; Takakuwa, Osamu*; Ogawa, Yuhei*; Yamaguchi, Masatake; Tsuzaki, Kaneaki*
no journal, ,
no abstracts in English
Moriyama, Junichiro*; Takakuwa, Osamu*; Yamaguchi, Masatake; Ogawa, Yuhei*; Tsuzaki, Kaneaki*
no journal, ,
In some austenitic stainless steels (Fe-Cr-Ni basic composition), hydrogen exhibits a high solution strengthening capacity with increasing solid solution hydrogen concentration that is difficult to explain by dimensional effects. In order to understand this phenomenon, it is necessary to understand the local hydrogen concentration in addition to the average solid solution hydrogen concentration in the Fe-Cr-Ni system. Since the average solid solution hydrogen concentration depends on the amount of Cr and Ni, the interaction between these substitutional atoms and hydrogen atoms is considered to be an important factor to focus on. In this study, first-principles calculations were used to quantify the interaction between Cr and Ni atoms and hydrogen atoms, and to evaluate the average solid-solution hydrogen concentration (occupancy) and its effect on the distribution.
