Computer simulation of phenomenological coefficients for atom transport in a random alloy

Abstract

Linear‐response theory provides general formulae for the phenomenological coefficients for atom transport defined by non-equilibrium thermodynamics. These formulae can be written in forms which are simple generalizations of the Einstein formula for tracer diffusion; they can therefore be calculated in a similar manner to tracer diffusion coefficients by Monte Carlo simulation of a system at thermodynamic equilibrium. The method is applied to calculate the phenomenological coefficients L_AA, L_BB , and L_AB =L_BA for a random f .c.c. alloy of components A and B with a very small concentration of vacancies. The diffusion coefficients of A and B are simply related to these coefficients. Compared with the simulation calculation of tracer correlation factors, larger numbers of vacancy jumps are needed to obtain acceptable statistics, particularly for the cross-coefficient L_AB- The results are in agreement with the theory of Manning (1971) within the accuracy attained.