Twinning disconnections and basal-prismatic twin boundary in magnesium

Recent experiments have revealed that the {1 0 (1) over bar 2} twin boundaries in hexagonal materials are decorated by (0 0 0 1)/{1 0 (1) over bar 0} basal-prismatic (BP) facets. The objective of this paper is to investigate the mechanism that leads to the formation of these BP interfaces using atomistic simulations and to carry out their stability analysis under an externally applied shear. We demonstrate that the stability of the BP interface is a consequence of large capillary forces that are caused by differences of the energies of a perfect {1 0 (1) over bar 2} twin boundary and the BP interface. The latter is formed by the glide of twinning disconnections and therefore agrees with the theory of admissible interfacial defects. This observation implies that the glide of twinning disconnections is a primary mechanism of the twin boundary migration.