LAUSR

Abstract c + a > dislocations and their interactions with other crystal defects in a Mg alloy have been investigated using atomic-resolution aberration-corrected scanning transmission electron microscopy. Two types of c + a > dislocations, with either a 60° or a screw a > component, were observed in Mg matrix, and both of them could form low-angle tilt grain boundaries during plastic deformation. c + a > dislocations could lead to migration of grain boundaries formed previously by a > dislocations in deformed Mg matrix. Moving c + a > dislocations cut and reacted with basal stacking faults, producing new defect structures during deformation. The mechanisms for interaction/reaction between c + a > dislocations and other defects are modeled based on atomic-resolution observations. These experimental results provide clear evidence for the occurrence of long range motion of c + a > dislocations with relatively compact cores during plastic deformation, instead of immediate dissociation on basal planes.