The contribution of the tracer correlation factor to the diffusion activation energy in intermetallic compounds

In this paper, the fraction of the activation energy for tracer diffusion t hat resides in the correlation factor is addressed in the: case of intermet allic compounds. We analysed the stoichiometric B2 structure with antistruc tural disorder. Two models-one, a mean-field treatment of the six-jump-cycl e mechanism, the other, a detailed treatment of the six-jump-cycle mechanis m-are considered. Monte Carlo computer simulation of an Ising-type alloy is used to provide an exact reference. It is shown that the detailed six-jump -cycle model provides the correct activation energy only at very low temper atures. On the other hand, the mean-held model provides a remarkably good d escription of the activation energy over a very wide temperature range. The findings are illustrated by application to CuZn. (C) 2000 Elsevier Science Ltd. All rights reserved.