Deformation Processes in the Intermediate Phase NiAl

Abstract

The activation energies and volumes of deformation have been evaluated from the effects of changes in strain rate and temperature on the flow stress of single-crystal and polycrystalline NiAl. The stress-dependence of these parameters, the appearance of slip-traces, and the agreement with a theoretical analysis are consistent with the rate-controlling mechanism at low temperatures being the nucleation of dislocation/kink pairs over a Peierls-Nabarro barrier. Deformation at high temperatures is complex and several mechanisms, including dislocation climb and cross-slip, appear to be important.