Dislocation facilitated formation and evolution of basal-prismatic/prismatic-basal interfaces in a Mg alloy

Formation and evolution of basal-prismatic/prismatic-basal (BP/PB) interfaces in a Mg alloy subjected to cyclic deformation were studied and modeled, according to atomic-resolution experimental observations and theory of interfacial defects. It is found that BP/PB interfaces could be formed by emission of 60° basal 1/3〈112¯0〉 dislocations (referred to as 〈a60〉), 〈c+a60〉 and {101¯2} twinning disconnections (TDs) from asymmetric tilt grain boundaries near the {101¯2} twin orientation. Transformation of BP/PB interfaces into {101¯2} twin boundaries could occur by emission of 〈a60〉 and 〈c+a60〉 dislocations, resulting in nucleation of {101¯2} twins. Moreover, each side of BP/PB facets could emit {101¯2} TDs to facilitate migration of BP/PB interfaces. Our experimental results may provide insights into the dislocation-assisted mechanisms of formation and evolution of BP/PB interfaces in hexagonal-close-packed materials.