The fundamental problem of chemical interdiffusion in binary alloys was considerd for the case where vacancies in non-equilibrium concentrations could be generated during interdiffusion. A very general phenomenological approach to interdiffusion was used, but was developed in a new way. Both high-vacancy and low-vacancy concentrations were dealt with. For commonly encountered small vacancy concentrations, the strategy was centred on incorporating information on the driving force associated with non-equilibrium vacancies - which was not really measurable - into the velocity of inert marker in the diffusion zone. Upon assuming access to independent knowledge of the 2 tracer diffusivities, expressions were derived for the transport coefficient (in the case of non-equilibrium vacancies) by using an analysis of Boltzmann-Matano type. By using the random-alloy model, it was shown that it was possible to measure the relative concentrations of the non-equilibrium vacancies produced during interdiffusion.

Analysis of Vacancies Produced at Non-Equilibrium Concentrations by Interdiffusion. I.V.Belova, G.E.Murch: Philosophical Magazine, 2005, 85[11], 1191-203