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Yamaguchi, Masatake; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito
Scripta Materialia, 255, p.116366_1 - 116366_5, 2025/01
Times Cited Count：0 Percentile：0.00(Nanoscience & Nanotechnology)Reduction of grain boundary cohesive energy by hydrogen has been considered as one of the candidate causes of grain boundary fracture in steels and aluminum alloys. Recently, the effects of grain boundary segregation elements have been investigated by first-principles calculations, but there are few studies that quantitatively estimate the grain boundary cohesive energy. In this study, we describe a quantitative evaluation method using first-principles calculation results and show some examples of experimental calculations.
Ying, H.*; Yang, X.*; He, H.*; Yan, A.*; An, K.*; Ke, Y.*; Wu, Z.*; Tang, S.*; Zhang, Z.*; Dong, H.*; et al.
Scripta Materialia, 250, p.116181_1 - 116181_7, 2024/09
Times Cited Count：1 Percentile：65.10(Nanoscience & Nanotechnology)Fang, W.*; Liu, C.*; Zhang, J.*; Xu, P. G.; Peng, T.*; Liu, B.*; Morooka, Satoshi; Yin, F.*
Scripta Materialia, 249, p.116046_1 - 116046_6, 2024/08
Times Cited Count：0 Percentile：0.00(Nanoscience & Nanotechnology)
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：1 Percentile：0.00(Nanoscience & Nanotechnology)Hydrogen 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.
Tang, J.*; Wang, Y.*; Fujihara, Hiro*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Ebihara, Kenichi; Takeuchi, Akihisa*; Uesugi, Masayuki*; Toda, Hiroyuki*
Scripta Materialia, 239, p.115804_1 - 115804_5, 2024/01
Times Cited Count：7 Percentile：68.31(Nanoscience & Nanotechnology)Stress corrosion cracking (SCC) behaviors induced by the combination of external and internal hydrogen (H) in an Al-Zn-Mg-Cu alloy were systematically investigated via in situ 3D characterization techniques. SCC of the Al-Zn-Mg-Cu alloy could initiate and propagate in the potential crack region where the H concentration exceeded a critical value, in which the nanoscopic H-induced decohesion of 
-MgZn
precipitates resulted in macroscopic cracking. External H that penetrated the alloy from the environment played a crucial role during the SCC of the Al-Zn-Mg-Cu alloy by generating gradient-distributed H-affected zones near the crack tips, which made Al alloys in water environment more sensitive to SCC. Additionally, the pre-existing internal H was driven toward the crack tips during plastic deformation. It was involved in the SCC and made contributions to both the cracks initiation and propagation.
Dannoshita, Hiroyuki*; Hasegawa, Hiroshi*; Higuchi, Sho*; Matsuda, Hiroshi*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Umezawa, Osamu*
Scripta Materialia, 236, p.115648_1 - 115648_5, 2023/11
Times Cited Count：1 Percentile：18.99(Nanoscience & Nanotechnology)
ders band deformation in an ultrafine grain stainless steel by combining 
neutron diffraction and digital image correlation analysisMao, W.; Gao, S.*; Gong, W.; Harjo, S.; Kawasaki, Takuro; Tsuji, Nobuhiro*
Scripta Materialia, 235, p.115642_1 - 115642_6, 2023/10
Times Cited Count：8 Percentile：83.19(Nanoscience & Nanotechnology)In the present study, a hybrid neutron diffraction and digital image correlation measurement was performed on tensile deformation of an ultrafine grain (UFG) stainless steel exhibiting a huge Lders band deformation to evaluate the individual contribution of the austenite matrix and the deformation-induced martensite to the strain hardening during the propagation of the band. Quantitative analysis revealed that the strain hardening of the austenite matrix was insufficient to maintain a uniform deformation when the flow stress was greatly enhanced by the UFG structure. The strain hardening required for the Lders band to propagate was mostly provided by the formation of martensite and the high internal stress within it.
neutron diffraction studyGong, W.; Kawasaki, Takuro; Zheng, R.*; Mayama, Tsuyoshi*; Sun, B.*; Aizawa, Kazuya; Harjo, S.; Tsuji, Nobuhiro*
Scripta Materialia, 225, p.115161_1 - 115161_5, 2023/03
Times Cited Count：7 Percentile：57.57(Nanoscience & Nanotechnology)Tsuchida, Noriyuki*; Ueji, Rintaro*; Gong, W.; Kawasaki, Takuro; Harjo, S.
Scripta Materialia, 222, p.115002_1 - 115002_6, 2023/01
Times Cited Count：8 Percentile：62.69(Nanoscience & Nanotechnology)Wei, D.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Kato, Hidemi*
Scripta Materialia, 216, p.114738_1 - 114738_6, 2022/07
Times Cited Count：43 Percentile：97.98(Nanoscience & Nanotechnology)Luo, M.-Y.*; Lam, T.-N.*; Wang, P.-T.*; Tsou, N.-T.*; Chang, Y.-J.*; Feng, R.*; Kawasaki, Takuro; Harjo, S.; Liaw, P. K.*; Yeh, A.-C.*; et al.
Scripta Materialia, 210, p.114459_1 - 114459_7, 2022/03
Times Cited Count：20 Percentile：90.09(Nanoscience & Nanotechnology)Shiihara, Yoshinori*; Kanazawa, Ryosuke*; Matsunaka, Daisuke*; Lobzenko, I.; Tsuru, Tomohito; Koyama, Masanori*; Mori, Hideki*
Scripta Materialia, 207, p.114268_1 - 114268_4, 2022/01
Times Cited Count：22 Percentile：82.48(Nanoscience & Nanotechnology)This study reports grain boundary (GB) energy calculations for 46 symmetric-tilt GBs in 
-iron using molecular mechanics based on an artificial neural network (ANN) potential and compares the results with calculations based on the density functional theory (DFT), the embedded atom method (EAM), and the modified EAM (MEAM). The results by the ANN potential are in excellent agreement with those of the DFT (5% on average), while the EAM and MEAM significantly differ from the DFT results (about 27% on average). In a uniaxial tensile calculation of GB, the ANN potential reproduced the brittle fracture tendency of the GB observed in the DFT while the EAM and MEAM mistakenly showed ductile behaviors. These results demonstrate the effectiveness of the ANN potential in calculating grain boundaries of iron, which is in high demand in modern industry.
Naeem, M.*; He, H.*; Harjo, S.; Kawasaki, Takuro; Zhang, F.*; Wang, B.*; Lan, S.*; Wu, Z.*; Wu, Y.*; Lu, Z.*; et al.
Scripta Materialia, 188, p.21 - 25, 2020/11
Times Cited Count：78 Percentile：98.11(Nanoscience & Nanotechnology)Yamashita, Takayuki; Morooka, Satoshi; Harjo, S.; Kawasaki, Takuro; Koga, Norimitsu*; Umezawa, Osamu*
Scripta Materialia, 177, p.6 - 10, 2020/03
Times Cited Count：34 Percentile：87.99(Nanoscience & Nanotechnology)
113
deformation twinning in metastable 
-type Ti alloy focusing on stress-induced 
martensite phaseCho, K.*; Morioka, Ryota*; Harjo, S.; Kawasaki, Takuro; Yasuda, Hiroyuki*
Scripta Materialia, 177, p.106 - 111, 2020/03
Times Cited Count：50 Percentile：94.23(Nanoscience & Nanotechnology)Shoji, Eita*; Isogai, Shosei*; Suzuki, Rikuto*; Kubo, Masaki*; Tsukada, Takao*; Kai, Tetsuya; Shinohara, Takenao; Matsumoto, Yoshihiro*; Fukuyama, Hiroyuki*
Scripta Materialia, 175, p.29 - 32, 2020/01
Times Cited Count：24 Percentile：77.46(Nanoscience & Nanotechnology)
neutron diffraction analysis during thermomechanical processingShibata, Akinobu*; Takeda, Yasunari*; Park, N.*; Zhao, L.*; Harjo, S.; Kawasaki, Takuro; Gong, W.*; Tsuji, Nobuhiro*
Scripta Materialia, 165, p.44 - 49, 2019/05
Times Cited Count：34 Percentile：85.33(Nanoscience & Nanotechnology) neutron diffraction study of phase stress evolution in a ferrous medium-entropy alloy under low-temperature tensile loadingBae, J. W.*; Kim, J. G.*; Park, J. M.*; Woo, W.*; Harjo, S.; Kim, H. S.*
Scripta Materialia, 165, p.60 - 63, 2019/05
Times Cited Count：34 Percentile：84.65(Nanoscience & Nanotechnology)Wang, B.*; He, H.*; Naeem, M.*; Lan, S.*; Harjo, S.; Kawasaki, Takuro; Nie, Y.*; Wang, X.-L.*; 7 of others*
Scripta Materialia, 155, p.54 - 57, 2018/10
Times Cited Count：67 Percentile：95.19(Nanoscience & Nanotechnology) neutron diffractionTomota, Yo*; Gong, W.*; Harjo, S.; Shinozaki, Tomoya*
Scripta Materialia, 133, p.79 - 82, 2017/05
Times Cited Count：28 Percentile：74.47(Nanoscience & Nanotechnology)
