The geometry of glide in Ni3Al at temperatures above the flow stress peak

At temperatures above the flow stress peak in Ni₃Al the slip system is 〈110〉{001}. At higher temperatures still a second system, 〈010〉{001}, also operates. Both types of dislocation form glide loops which dissociate into $\text{1}\text{2}$ 〈110〉 APB-linked partials and both glide loops show ranges of elastic instability. Three types of dislocation may lower their energy further by a second dissociation on {111} planes: the screw 〈110〉 forms a Kear-Wilsdorf lock, the edge 〈110〉 forms a Lomer-Cottrell lock and the 45° 〈010〉 forms a B5 lock. Interactions between 〈110〉 and 〈010〉 dislocations give rise to two more dislocations with non-planar cores, the 〈110〉 lock and the 〈111〉 lock. All these locked dislocations are slow moving or immobile and all, except for the 〈111〉 lock, have been observed in the electron microscope. The formation of 〈110〉 and 〈111〉 locks and the mixing of the two slip systems through interactions between them give an explanation for the high-temperature work-hardening peak found in Ni₃Al.