Atomic transport in a random alloy at arbitrary vacancy concentration

Abstract

For a random alloy with a very small vacancy concentration c_v the theory of Manning (1971, Phys. Rev. B, 4, 1111) provides accurate predictions of all of the phenomenological atomic transport coefficients L_xy of non-equilibrium thermodynamics. A natural extension of these results to arbitrary vacancy content is sought. An earlier decoupling scheme for the hierarchy of time-correlation functions encountered in the analysis of the linear-response expression for L_xy is reformulated and extended to arbitrary c_v. The final results generalize all Manning's results in a very simple manner and reduce to them for c_v ←0. The predicted tracer correlation factors at large c_v- are in poorer agreement with simulation results than those for c_v←0. These results suggest that a simple and natural generalization of the complete Manning structure of relationships between the various transport coefficients of comparable accuracy to the original theory for c_v←0 may not be readily found.