Zonal twinning dislocations in body centred cubic crystals

Abstract

A computer simulation study of steps in b.c.c. twin boundaries has resulted in the discovery of an unexpected type of twinning dislocation. The defect has the same Burgers vector as the conventional perfect twinning dislocation but is associated with a double interfacial step in the opposite sense. It therefore has a low self energy but zonal character. Its structure is examined and the operation of the corresponding twinning mode discussed. It is suggested that this defect may play a significant role in the interaction of slip and twin boundaries in b.c.c. metals.