Glide sequences of deformation in the {111} plane of Ni₃Ga single crystals in the yield stress anomaly

Abstract

Ni₃Ga single crystals oriented parallel to the [123] direction were deformed in the range of the yield stress anomaly. Successive deformations have also been performed at different temperatures on the same specimen. The substructure of dislocations in the (111) plane has been observed by weak-beam microscopy. The screw dislocations are in the Kear-Wilsdorf configuration and contain many superkinks, the shape of which has been analysed. Simple superkinks and switchover superkinks have been observed. A statistical analysis of the superkink height has revealed two types of deformation sequence. The locking process corresponding to one of these is thermally activated while that of the other has a geometric cause.