Interdiffusivity and Ratio of Intrinsic Diffusivities in Ag–Zn Alloys

Interdiffusion coefficients in Ag–Zn α phase in the temperature range between 823 and 1023 K have been determined by Sauer and Freise analysis using solid-solid diffusion couples consisting of pure silver and a 20 at%Zn–Ag alloy. From the Sauer and Freise’s and the Darkens’s equations, a simple expression for the ratio of the intrinsic diffusivities with respect to the mole-fixed frame of reference can be derived. Using the expression, the ratio DZnN⁄DAgN at 1023 K has been determined. With the aid of the ratios DZnN⁄DAgN determined in this investigation and the ones previously determined by the vapor-thin plate diffusion couples, the vacancy flow factor, G, in the infinitely dilute state has been estimated to be −0.55 at 1023 K. By combining the value for G with the known solute enhancement factor for solvent diffusion the correlation factor for impurity diffusion of Zn in Ag has been evaluated.