SOLUTE ENHANCEMENT OF SILVER SELF-DIFFUSION IN SILVER-TIN ALLOYS AT LOW-TEMPERATURES

Measurements of the diffusion of Ag-110m in Ag-Sn alloys over the temperature range 618-654 K and 0 to 4.5 at.% Sn have been carried out by means of the ion-beam sputtering technique for serial sectioning. A strong non-linear enhancement of solvent diffusion upon alloying was observed. The Gibbs free energy (-g(b1)) of vacancy-impurity binding was calculated from the data. Comparison with earlier high-temperature measurements reveals that g(b1) decreases substantially with decreasing temperature. At 1000 K g(b1) = 0.20 eV is observed in good agreement with results from measurements of the absolute vacancy concentration.