純マグネシウム中の〈a〉らせん転位の交差すべり機構に関する原子論的研究

Abstract

To understand the cross-slip mechanism of 〈a〉 screw dislocations on the basal and prismatic slip planes, we evaluate the shear-stress dependence of activation energy for kink-pair nucleation (and migration) processes based on atomistic modeling, which are the dominant, rate-controlling steps for screw dislocation motion in Mg. Using the energetics, the critical resolved shear stresses (CRSS) for basal and prismatic slip planes are obtained according to the Orowan's eqation. The estimated CRSS for the basal plane is quite low because of the low activation energy of kink-pair nucleation on the basal plane. The result suggests that the difference in kink-pair nucleation mechanism between the basal and prismatic planes is a key facter to understand the characteristic temperature dependence of CRSS for these slip systems in Mg.