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Tsuru, Tomohito; Mayama, Tsuyoshi*
Keikinzoku, 74(9), p.442 - 450, 2024/09
Magnesium (Mg) alloys have a wide range of expanding applications as structural materials and biomaterials. On the other hand, there is room for improvement in mechanical properties and corrosion resistance, and there are many issues related to structural design and prediction of deformation behavior due to their remarkable plastic anisotropy, and material development based on material/process design is still actively conducted. In this paper, as computational materials science research into the mechanical properties of Mg alloys, we introduce a method for non-empirical evaluation of the effect of alloying on mechanical properties using first-principles calculations, and an analysis method for polycrystalline behavior and non-uniform deformation using the crystal plasticity finite element method, together with specific analysis examples.
Fujihara, Hiro*; Toda, Hiroyuki*; Ebihara, Kenichi; Kobayashi, Masakazu*; Mayama, Tsuyoshi*; Hirayama, Kyosuke*; Shimizu, Kazuyuki*; Takeuchi, Akihisa*; Uesugi, Masayuki*
International Journal of Plasticity, 174, p.103897_1 - 103897_22, 2024/03
Times Cited Count：9 Percentile：93.27(Engineering, Mechanical)Hydrogen(H) embrittlement in high-strength aluminum(Al) alloys is a crucial problem. H accumulation at the interface of precipitates in Al alloy is considered to cause embrittlement. However, there is no quantitative knowledge regarding the interaction between H distribution and stress field near cracks. In this study, using a multi-modal three-dimensional image-based simulation combining the crystal plasticity finite element method and H diffusion analysis, we tried to capture the stress distribution near the crack, its influence on the H distribution, and the probability of crack initiation in the experimental condition. As a result, it was found that grain boundary cracks transition to quasi-cleavage cracks in the region where the cohesive energy of the semi-coherent interface of MgZn
precipitates decreases due to H accumulation near the tip. We believe the present simulation method successfully bridges nanoscale delamination and macroscale brittle fracture.
Hagihara, Koji*; Mayama, Tsuyoshi*; Yamasaki, Michiaki*; Harjo, S.; Tokunaga, Toko*; Yamamoto, Kazuki*; Sugita, Mika*; Aoyama, Kairi*; Gong, W.; Nishimoto, Soya*
International Journal of Plasticity, 173, p.103865_1 - 103865_21, 2024/02
Times Cited Count：24 Percentile：98.62(Engineering, Mechanical)
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：9 Percentile：58.32(Nanoscience & Nanotechnology)
Mg/LPSO dual-phase magnesium alloy monitored by 
neutron diffractionHarjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*; Mayama, Tsuyoshi*; Kawamura, Yoshihito*
Materials Transactions, 64(4), p.766 - 773, 2023/02
Times Cited Count：8 Percentile：70.14(Materials Science, Multidisciplinary)Gong, W.; Harjo, S.; Mayama, Tsuyoshi*; Kawasaki, Takuro; Aizawa, Kazuya; Sun, B.*; Tsuji, Nobuhiro*
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In situ neutron diffraction experiments at cryogenic temperature was performed to investigate the temperature dependence of deformation behavior and corresponding activities of deformation mechanisms in a commercial AZ31 Mg alloy. The stress-strain curve at 21K showed slightly higher macroscopic yield stress but remarkably higher fracture stress and strain than that of room temperature. The enhancement of extension twinning and suppression of contraction twinning at cryogenic temperature are considered to be the reasons for improving the corresponding macroscopic strength and ductility in the commercial AZ31 alloy.
Koyama, Motomichi*; Hojo, Tomohiko*; Miyamoto, Goro*; Morooka, Satoshi; Yamashita, Takayuki; Sawaguchi, Takahiro*; Mine, Yoji*; Mayama, Tsuyoshi*; Okitsu, Takayuki*; Sakakibara, Mutsumi*; et al.
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no abstracts in English
Gong, W.; Harjo, S.; Mayama, Tsuyoshi*; Kawasaki, Takuro; Aizawa, Kazuya; Sun, B.*; Tsuji, Nobuhiro*
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Gong, W.; Harjo, S.; Mayama, Tsuyoshi*; Kawasaki, Takuro; Aizawa, Kazuya; Tsuji, Nobuhiro*
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Gong, W.; Kawasaki, Takuro; Zheng, R.*; Mayama, Tsuyoshi*; Aizawa, Kazuya; Harjo, S.; Tsuji, Nobuhiro*
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Gong, W.; Kawasaki, Takuro; Harjo, S.; Zheng, R.*; Mayama, Tsuyoshi*; Aizawa, Kazuya; Tsuji, Nobuhiro*
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