Solute bulk diffusion during high-temperature plastic deformation in a substitutional solid solution alloy was analyzed theoretically. Both the deformation-induced supersaturated vacancy enhanced diffusion effect and dislocation pipe diffusion effect were considered in the model. The latter was applied to the prediction of deformation-enhanced phosphorus diffusion in γ-Fe. Deformation-induced supersaturated vacancy enhanced diffusion and pipe diffusion could both enhance the overall phosphorus diffusion coefficient, but the former effect played a predominant role. At a certain temperature, the deformation-enhanced phosphorus diffusion coefficient was mainly dependent upon strain and strain rate, and at each strain rate there was a steady state value for the enhanced diffusion coefficient. In one example, the phosphorus lattice diffusion coefficient, pipe diffusion coefficient and deformation-induced supersaturated vacancy enhanced diffusion coefficient were predicted as a function of strain, for a strain-rate of 2.5 x 10-3/s at 950C. The lattice diffusion and pipe diffusion coefficients were constant during deformation, while the supersaturated vacancy enhanced diffusion coefficient increased with increasing strain; reaching a steady value at a strain of some 7%. The supersaturated vacancy enhanced diffusion and pipe diffusion coefficients were both much higher than the lattice diffusion coefficient. The deformation-enhanced diffusion was due to the combined effect of supersaturated vacancy enhanced diffusion and pipe diffusion. In some cases, the deformation-induced supersaturated vacancy enhanced diffusion played a key role in the deformation-enhanced diffusion while the pipe diffusion effect was very small. This was because although the pipe diffusion coefficient was about two orders of magnitude higher than the steady value of the supersaturated vacancy enhanced diffusion coefficient, the ratio of solute atoms associated with the dislocation was too low. In the case of the temperature dependence of the deformation-enhanced diffusion coefficient with supersaturated vacancy enhanced diffusion and pipe diffusion coefficients, after 10% strain at a rate of 2.5 x 10-3/s, the deformation-enhanced diffusion coefficient increased drastically with rising temperature above 900C. In addition, the supersaturated vacancy-enhanced diffusion effect was predominant over the whole temperature range considered. The overall deformation-enhanced diffusion increased with increasing strain rate, and the contribution from supersaturated vacancy enhanced diffusion was predominant.

Solute Diffusion During High-Temperature Plastic Deformation in Alloys. S.H.Song, X.M.Chen, L.Q.Weng: Materials Science and Engineering A, 2011, 528[24], 7196-9