OS0114 原子シミュレーションによる種々の応力環境下でのマグネシウム単結晶中の転位生成の定量的解析

抄録

For wide application of magnesium(Mg), it is necessary to quantitatively evaluate the activation condition of each deformation mode observed in deformation experiments of Mg. In usual experiments, critical resolved shear stress(CRSS) is used for quantitative evaluation of deformation. However, recent work on deformation of Mg via atomistic simulations indicates that normal stresses applied in the crystal also contribute to CRSS. In this work, we evaluate the activation free energy of the nucleation of a basal edge dislocation pair in an Mg single crystal under the application of the shear stress in slip direction and the normal stress in one direction via atomistic simulations. Our results show that the activation free energy of a dislocation nucleation is strongly dependent on the normal stresses along [1120] and [0001] directions though it is not sensitive to the normal stress along [T100] direction. We attribute this dependence to the elastic deformation of the crystal due to the normal stress, which brings the change in the magnitude of Burgers vector and distance between atomic planes.