Deformation-induced point defects in NiAl single crystals

Abstract

NiAl single crystals, oriented for single slip, were deformed at room temperature to a strain of 2%, and were subsequently annealed in the temperature range of 673–873 K ( T/T m =0.35–0.45). In as-deformed samples, dislocation substructures consist of jogged edge and screw dislocations, and prismatic loops. Densities of vacancy- and interstitial-type loops are about equal. Annealing causes shrinkage and disappearance of the interstitial loops and significant growth of the vacancy loops. These observations suggest that excess vacancies are present after room temperature deformation. These non-equilibrium point defects may result from non-conservative motion of jogged screw dislocations.