粒界を跨ぐ変形の連結性に関する原子シミュレーション

抄録

To investigate the mechanism for localization of plastic deformation in polycrystals, we proposed a parameter that expresses the resistance to propagation of sliding deformation across grain boundaries and examined the relationship between the connectivity of deformation propagation across grain boundaries and microstructure by creating a polycrystal model that takes this parameter into account. We proposed a parameter M' that combines the geometrical relationship between the lattice orientation of neighboring grains and the Schmid factor as a mechanical element. To examine the effect of the grain boundary properties on the connectivity of plastic deformation, two different polycrystalline models were created: the first one is a reference model consisting only of grain boundaries with small M', and the second is a model in which a small group of grains with large M' is introduced into the reference model, and uniaxial tensile tests were performed to the models. In the case of the reference model with small M', the slip deformation occurs from various grain boundaries, resulting in homogeneous plastic deformation. On the other hands, in the case of the model with a small group of grains with large M', plastic deformation occurred from the grain boundaries with large M' and localized plastic deformation was formed. This trend was more pronounced as the small group of grains increased. Furthermore, the strength of the polycrystalline models was strongly influenced by the degree of the localized plastic deformation.