長周期積層構造(LPSO)相を有するMg二相合金は，微細なキンク帯形成によって飛躍的に力学特性が向上する．本研究では，キンク帯形成による材料強化機構を解明するため，Cosseratモデルを有限変形理論の体系で結晶塑性論的に定式化し，転位蓄積と回位発生を同時に考慮した材料モデルを構築した．また，得られたモデルを用いて短冊形三結晶に対してメッシュフリー解析を実施し，圧縮負荷によるキンク帯形成後に逆負荷を作用させると，Ridge形キンクが発生し易いほど局所方位差および転位が多く残存して終端強度が増大すること，ならびにα-Mg相の平均粒径が小さいほど逆負荷後の終端強度がさらに上昇することを示した．
The mechanical properties of Mg dual-phase alloys with long-period stacking ordered (LPSO) phase are significantly enhanced by the formation of fine kink bands. In this study, to clarify the strengthening mechanism owing to the kink bands, the Cosserat model was formulated in the framework of crystal plasticity based on finite deformation theory and a new material model was developed, in which the accumulation of dislocations and the generation of disclinations were simultaneously considered. Using the obtained model, a mesh-free analysis was performed for a strip-shaped tri-crystal. As a result, it was showed that when a kink band is formed by compressive loading and then reverse loading is applied, if ridge-shaped kinks tend to occur, local orientation differences and accumulated dislocations remain more, and the terminal strength is higher. In addition, the smaller the average grain size of the α-Mg phase becomes, the higher the terminal strength after reverse loading reaches. 

研究種目 : 基盤研究 (C) (一般)
研究期間 : 2020～2022
課題番号 : 20K04165
研究分野 : 計算材料科学