Characterization of the matrix–twin interface of a (101̄2) twin during growth

Abstract

A model of twin growth in magnesium is presented together with the analysis of defects responsible for this growth. The twin interface is represented by and basal-prismatic facets. Disclinations are situated in the facet junctions creating dipoles superimposed on basal-prismatic and conjugate twin facets. The migration of facets is mediated by the conservative motion of interfacial disconnections. The interfaces contain twinning disconnections. The facet junctions serve as sources and sinks for these defects. Two types of disconnections ( and ) were observed in basal-prismatic boundary. The dipoles of disconnections were nucleated in the vicinity of existing defects of this type. Interaction of this dipole with existing leads to the creation of a disconnection, which is later absorbed in the facet junction. The nucleation of dipoles was not observed. In twin embryo growth, the basal-prismatic segments remain coherent with a fixed length, while the twin segments grow indefinitely.