The six-jump cycle diffusion mechanism in non-stoichiometric B2 intermetallics: the vacancy-wind factor

In this paper we explore the behaviour of the vacancy-wind factor or Manning factor for chemical diffusion in antistructurally disordered intermetallics taking the B2 structure. The analytical formalism is based on generalized six-jump- cycles providing the vehicles for diffusion of both components. Comparison of the analytical results is made with results from Monte Carlo calculations based only on single vacancy jumps. Very good agreement is found at low temperatures/ high levels of order where it can be anticipated that six-jump-cycles dominate the diffusion process. In such circumstances, a first (rough) approximation, it would be reasonable to put the vacancy-wind factor/Manning factor equal to 0.5 rather than unity as is often done.