Twinning nucleation in Cu-8 at. % Al single crystals

Transmission electron microscopy observations of the dislocation substructure in Cu-8at.% Al single crystals deformed in tension have been carried out to elucidate the origin of the twinning dislocation which produces conjugate twinning in this alloy. It is argued that the ‘correct’ Heidenreich-Shockley dislocation is obtained in the reaction of the primary dislocation with the faulted (Frank) dipole. These interactions are expected to occur …