Atomistic Study of the Interaction between Dislocations and Structural Point Defects in NiAl

Abstract

The interaction of (100), (110) and (111) dislocations with structural point defects in NiAl has been studied by atomistic computer simulations using embedded atom type potentials. The relaxed atomic configurations of Ni antisite defects and Ni vacancies near the dislocation cores have been obtained from static energy minimization. The depinning stresses and the binding energy profiles have been determined to characterize the strength of the interaction between the individual point defect and the dislocation. Based on these results, the increase in yield strength of NiAl single crystals with deviation from stoichiometry was calculated using Fleischer's theory of solid solution hardening. However, experimental results show a much larger effect, suggesting that more complex defeet structures may play an important role.