A thin twin and its interaction with a coherent twin boundary in copper

Abstract

Abstract An electron microscope investigation has been conducted of a thin twin intersecting an existing coherent twin boundary (CTB) in copper. The twin crystallography and dislocations associated with it and its interaction with the CTB have been experimentally determined. It appears that when a twinning dislocation intersects a CTB, it undergoes a dissociation reaction so as to facilitate the distribution of twinning strain in various directions and thus prevent the stress build-up at the twin-CTB interface. The proposed reaction, even though energetically unfavourable, could occur under the influence of the stress concentration that exists at the head of the pile-up of twinning dislocations.