Modeling of Diffusion in Ordered Structures of B2-Type

Abstract

ABSTRACTUsing Monte Carlo simulation, we model the effect of interaction of vacancies on their diffusivities in ordered structures of B2-type. The activation barriers of atom jumps to vacancy are calculated by the static relaxation technique using interatomic potentials for both vacancy exchanges: with nearest-neighbour atoms and next-nearest-neighbour atoms. This is done for all possible positions of the second vacancy. Knowing these barriers it is possible to calculate the jump rates and to model the vacancy migration. The calculations were done for a system with parameters similar to NiAl. The modeling allows to inter the existence of a new diffusion mechanism in ordered structures of B2-type, which could be attributable to dynamic pair of vacancies and vacancy exchanges with next-nearest-neighbor atoms.