Nucleation of elementary {(1)over-bar 0 1 1} and {(1)over-bar 0 1 3} twinning dislocations at a twin boundary in hexagonal close-packed crystals

In this paper, we study the kinetics and energetics involved in the nucleation and propagation of {(1) over bar 0 1 1} and {(1) over bar 0 1 3} twinning dislocations (TDs) in Mg using atomistic simulations. We demonstrate that for both twins, a 2-layer TD of mixed character nucleates as a result of the interaction of a basal dislocation with a twin boundary. The favorability of the 2-layer TD over a 4-layer TD of edge character can be explained by its greater mobility. The twin boundary likely translates by nucleating and propagating 2-layer TDs with opposite-signed screw components in equal amounts on average.