Multi-phase-fieldモデルおよび転位–結晶塑性モデルに基づくLPSO型Mg二相合金に対する動的再結晶シミュレーション

抄録

A dual-phase magnesium alloy consisting of the usual α-Mg phase and a new LPSO (Long-Period Stacking Ordered Structure) phase has been developed and expected for a next-generation structural material owing to its excellent mechanical properties. Its materials strengthening is attributed to both the grain refinement of α-Mg phase generating in the process of dynamic recrystallization and a kink band formations in LPSO phase. In this paper, we develope a dynamic recrystallization model for HCP crystals by coupling the multi-phase-field (MPF) model and the dislocation-based crystal plasticity model through the dislocation density considering material properties of Mg/LPSO alloys. It is widely known that the pinning effect affects the grain refinement in α-Mg phase. Such effect is expressed by taking account of the grain boundary segregation of additional elements. In addition, some multiphysics analyses for Mg/LPSO alloys are carried out, and then nucleation along deformation bands such as kink bands and nucleus growth are numerically reproduced. Furthermore, on the basis of the obtained results, it is indicated that a kink band generates primarily around an α-Mg phase with orientation imperfection, a grain-refinement in α-Mg phase occurs secondarily along a deformation band as a prolongation of the kink band in LPSO phase.