The vacancy wind effect for chemical diffusion in intermetallic compounds

Abstract

In this paper we examine the behaviour of the vacancy wind factors in the intrinsic diffusivities and the chemical or interdiffusivity in highly ordered stoichiometric AB intermetallic compounds. We show that the six-jump cycle gives quite different limits for these factors from those given by the well-known Manning expressions. Remarkably, there is non-trivial behaviour of these factors even when the vacancy flux is zero. The findings are all verified by computer simulations of a four-frequency model in the square planar lattice and an Ising model in the B2 structure. The consequences of the findings for the interpretation of experimental data are commented on.