A simple model was considered, for the description of chemical diffusion in a long-range ordered alloy, in which the sub-lattice existed  a priori. Diffusion was assumed to take place via vacancies. Four atom-vacancy exchange frequencies were specified. The Mannings formalism for describing diffusion in a random alloy was extended to the present model. The thermodynamic factors were calculated by modifying the Widom formalism. The average jump frequencies and thermodynamic factors were calculated exactly. The calculated collective correlation factors, which were combined in the vacancy wind terms of intrinsic diffusivities, were found to be in good agreement with Monte Carlo computer simulation results.

I.V.Belova, G.E.Murch: Philosophical Magazine A, 1996, 73[6], 1699-713