Solvent self-diffusion in dilute b.c.c. solid solutions

Abstract

Abstract This paper completes and extends the calculations previously made (Le Claire 1970 a) of the influence of small concentrations of solute on the solvent self-diffusion rate in dilute b.c.c. substitutional solid solutions. Proper account is now taken of correlation effects in the solvent diffusion: mean partial correlation factors are calculated and tabulated as functions of the appropriate atom jump frequency ratios. The calculations are performed for two dilute solution models, differing in the assumptions made about the effects of the solute on the solvent jump frequencies and on the extent of vacancy-solute binding. One model, assuming binding at both 1st and 2nd neighbour distances, is the same as was discussed in the previous paper. The second model assumes vacancy-solute binding at the 1st neighbour separation only and that all dissociative vacancy jumps from nearest-neighbour sites of a solute atom occur at the same frequency. The results of the calculations, for both models, are used to discuss experimental data on dilute b.c.c. solid solutions.