Interdiffusion and intrinsic diffusion in binary vanadium-titanium solid solutions at 1350°C

Abstract

Interdiffusion coefficients, intrinsic diffusion coefficients, and vacancy wind parameters have been determined in the vanadium-titanium system at 1350°C with the use of infinite, solid-solid diffusion couples. The experimentally determined diffusion coefficients were compared with the values predicted from the models of Darken, Manning and Dayananda with the use of available tracer diffusion and thermodynamic information and were found to be larger than those calculated from the three models. Vacancy wind parameters, determined experimentally, were seen to reflect a greater influence of the vacancy wind phenomenon on the intrinsic diffusion flux of each species than that calculated on the basis of Manning’s theory. In particular, the faster diffusing component is enhanced and the slower diffusing component is retarded to a greater degree than is theoretically predicted. Furthermore, experimental and predicted values of intrinsic diffusivity ratios,D _V /D _Ti ,were compared and the results suggest an increased effect of vacancy flow on the intrinsic fluxes with respect to the magnitude of this phenomenon calculated from Manning’s treatment. The vacancy wind effect is shown to be an important factor in the consideration of intrinsic diffusion fluxes and their relation to tracer diffusion and thermodynamic information in the vanadium-titanium system.