We have measured the diffusion of gold in lead to pressures of 46 kbar and temperatures of 420 °C using a radioactive-tracer technique. The data were analyzed assuming a single effective mechanism of diffusion with a temperature- and pressure-dependent activation volume. The earlier data on the diffusion of silver in lead by Curtin, Decker, and Vanfleet were also analyzed in a similar manner. The activation energy and activation volume at the melting point and atmospheric pressure are, respectively, $\Delta H=9.48\mathrm{}\pm 0.30$ kcal per mole, $\frac{\Delta V}{V_0}=0.28\mathrm{}\pm 0.03$ for Au in Pb: $\Delta H=14.63\mathrm{}\pm 0.24$ kcal per mole, $\frac{\Delta V}{V_0}=0.34\mathrm{}\pm 0.04$ for Ag in Pb. Although no definite conclusion as to the specific nature of the diffusion mechanism can be drawn, the results are not inconsistent with an interstitial-substitutional double mechanism.

• Received 2 August 1971

DOI:https://doi.org/10.1103/PhysRevB.4.4225