Rapid work hardening caused by cube cross slip in Ni₃Al single crystals

Abstract

Dislocation structures introduced by deformation at various temperatures in the anomalous strengthening region in Ni₃Al single crystals have been examined using high voltage electron microscopy with special care in preserving the bulk structure after deformation. The three-dimensional dislocation structures found by stereo microscopy have been analysed and correlated with the high-temperature strengthening. It is shown that the rapid work hardening leading to the anomalous strengthening is essentially controlled by the Kear-Wilsdorf locking or the (010) cross slip and is not affected by the secondary slip. The origin of the transition in the strain-rate sensitivity has also been considered and is attributed to the transition in the hardening mechanism due to (010) cross slip.