Tracer C diffusion, chemical diffusion and C activity data in austenite in terms of a 4-frequency interstitial model first formulated by McKee was analyzed. The later formulation by Okamura and Allnatt, which has recently been confirmed to be essentially exact, was made use of. In the revised analysis, the general finding of McKee that the increase of both tracer and chemical C diffusion coefficients with C composition at 1000C was largely a result of a much higher rate of rotation of an interstitial pair compared with isolated C atoms was confirmed. It was found that C atoms move almost 2 times faster as a rotating pair than established originally by McKee. Information on the ratios of the exchange frequencies to other temperatures between 800 and 1000C using the available experimental data on the intrinsic diffusivities and the C activity was extrapolated.

Analysis of Carbon Diffusion in Austenite Revisited. I.V.Belova, G.E.Murch: Philosophical Magazine, 2005, 85[36], 4515-23