Dislocation Mobilities in NiAl From Molecular Dynamics Simulations

Abstract

ABSTRACTUsing the Voter-Chen Embedded Atom Method (EAM) potentials for the Ni-Al alloy system,the Peierls stress (σp) and velocity of edge dislocations (b=[100]) have been estimated in stoichiometric perfectly ordered B2 NiAIat a temperature of 10 K, by the use of molecular dynamics simulations employing approximately 4000 atoms. σp was determined to be about 3×1010 dynes/cm2, or about 2%of the shear modulus, C44. The steady state velocity was found to be about 1.6×105 cm/s (or 65% of the (001) shear velocity) under an applied shear stress of 3.9×1010 dynes/cm2. Stress induced martensite (SIM) was nucleated in some of the simulations after the dislocation had begun to move, and in all cases when the SIM reached the immediate neighborhood of the dislocation core the motion of the dislocation was arrested.