Using a new simulation approach to the calculation of correlation factors in very dilute solutions, the first calculations were made of the first and second solute enhancement factors for solute self-diffusion in the 14-frequency model postulated for describing the diffusion kinetics of paired and unpaired solute atoms in dilute face-centered cubic alloys. The assumption that correlation effects did not contribute to solute self-diffusion enhancement was shown to have a quite limited range of validity. It was shown that this assumption was reasonable when the solvent-vacancy exchange frequency far from the solute was high when compared with the others, or when all of the solute-vacancy exchange frequencies were small compared with the others. The assumption was also reasonable when the vacancy was not attracted to solute atoms and when the vacancy did not frequently alternate between 2 solute atoms. The present study strongly suggested that many of the ratios of exchange frequencies, that were determined from experimental data on the basis of this assumption, were likely to be wrong.

Enhancement of Solute Self-Diffusion in FCC Alloys. I.V.Belova, G.E.Murch: Philosophical Magazine, 2006, 86[12], 1615-29