The vacancy wind effect for chemical diffusion in intermetallic compounds

In this paper we examine the behaviour of the vacancy wind factors in the i ntrinsic diffusivities and the chemical or interdiffusivity in highly order ed stoichiometric AB intermetallic compounds. We show that the six-jump cyc le gives quite different limits for these factors from those given by the w ell-known Manning expressions. Remarkably, there is non-trivial behaviour o f these factors even when the vacancy flux is zero. The findings are all ve rified by computer simulations of a four-frequency model in the square plan ar lattice and an Ising model in the B2 structure. The consequences of the findings for the interpretation of experimental data are commented on.