Interaction between migrating [formula omitted] twin boundary and extended 〈 a 〉 dislocations inside twin in pure Mg

Abstract

Interaction between a matrix prismatic 〈 c 〉 edge dislocation and a migrating (101¯2) twin boundary results in extended basal 〈 a 〉 mixed dislocations in the twin lattice. The interaction between the resultant 〈 a 〉 dislocation and the migrating twin boundary is studied using molecular dynamics simulations. The 〈 a 〉 dislocation tends to detach from or connect to the twin boundary, when its slip plane intersects a compression or extension site of the twin boundary. When the 〈 a 〉 dislocation connects to the twin boundary, connection always occurs with a 90° Shockley partial and a basal-prismatic (BP) or prismatic-basal (PB) two-atomic-layer-height step, depending on whether the Burgers vector direction of the Shockley partial points away from or towards the twin boundary. The BP or PB two-atomic-layer-height step is sessile, in contrast to those that are not connected to such 〈 a 〉 dislocation.