Dislocation motion in magnesium: a study by molecular statics and molecular dynamics

Abstract

The motion of dislocations with Burgers' vector lying on the basal, prismatic and pyramidal slip planes in pure magnesium was investigated numerically under static and dynamic loading conditions. The analysis of the dislocation core structures revealed that the basal slip system was the most favorable energetically, and therefore a dislocation loop cannot extend on the pyramidal slip plane, because screw dislocations were not stable in this slip plane. In agreement with experimental data, a strong anisotropy between slip systems was observed. In both the basal and the prismatic slip planes, the dislocation velocity is consistent with phonon drag theory. In addition, the edge dislocation velocity was always larger than the screw dislocation velocity independent of the slip system, while the dislocation velocity on the prismatic slip plane was always lower than the dislocation velocity on the basal plane regardless of the dislocation character.