It was pointed out that intermetallic compounds containing high concentrations of structural vacancies had made the determination of interdiffusivity, from the composition profile of a diffusion couple, a confusing issue. Here, an exact procedure was formulated from fundamental principles. The only assumption made was the use of the Gibbs-Duhem relationship. It was shown that the standard procedure for analysing composition profiles in diffusion couples slightly overestimated the interdiffusivity. It was also shown that a proposed procedure for analyzing composition profiles in NiAl was incorrect near to the stoichiometric composition, where it seriously underestimated the interdiffusivity.
Analysis of Composition Profiles to Obtain Interdiffusion Coefficients in Binary Intermetallic Compounds. I.V.Belova, G.E.Murch: Philosophical Magazine, 2004, 84, 3655-62