STATISTICAL DERIVATION OF BASIC EQUATIONS OF DIFFUSIONAL KINETICS IN ALLOYS WITH APPLICATION TO THE DESCRIPTION OF DIFFUSION OF CARBON IN AUSTENITE
Vaks V.G., Zhuravlev I.A.

Received: February 26, 2012

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Basic equations of diffusional kinetics in alloys are statistically derived using the master equation approach. To describe diffusional transformations in substitution alloys, we derive the ``quasi-equilibrium'' kinetic equation that generalizes its earlier versions by taking possible ``interaction renormalization'' effects into account. For the interstitial alloys Me-X, we derive an explicit expression for the diffusivity D of an interstitial atom X. This expression notably differs from those used in previous phenomenological treatments. This microscopic expression for D is applied to describe the diffusion of carbon in austenite based on some simple models of carbon-carbon interaction. The results obtained enable us to make certain conclusions about the real form of these interactions and about the scale of the ``transition state entropy'' for diffusion of carbon in austenite.