At temperatures above the flow stress peak in Ni3Al the slip system was <110>{001}. At higher temperatures still a second system, <010>{001}, also operates. Both types of dislocation form glide loops which dissociate into ½<110> antiphase boundary-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> formed a Kear-Wilsdorf lock, the edge <110> formed a Lomer-Cottrell lock and the 45°<010> formed 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 were slow moving or immobile and all, except for the <111> lock, were 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.

The Geometry of Glide in Ni3Al at Temperatures above the Flow Stress Peak. Hazzledine, P.M., Yoo, M.H., Sun, Y.Q.: Acta Metallurgica, 1989, 37[12], 3235-44