A new analysis of diffusion in ternary alloys: application to f.c.c Fe-Ni-Cr alloys

In the present paper we develop new procedures for analysing chemical diffusion data in ternary alloys in order to provide ratios of atom-vacancy exchange frequencies. We base the procedures on the diffusion kinetics formalisms conceived by Manning and Moleko et al. As a reference point we also consider the simple formalism in which off-diagonal phenomenological coefficients are neglected. We apply the procedures to the measured interdiffusion coefficients in the γ-austenite phase of the Fe-Ni-Cr system at 1100 °C. We show that the ratios of atom-vacancy exchange frequencies determined are reasonably consistent with those obtained from the tracer diffusion data using the same formalisms. We show that the three procedures give quite similar results for the frequency ratios in this alloy system where the atomic components have similar sizes and diffusivities.