Interstitial Diffusion of Copper in Lead at Pressures up to 56 kbar

The diffusion of copper in lead has been investigated using radioactive-tracer and sectioning techniques. The measured diffusion coefficients span the hydrostatic pressure range 0---56 kbar and temperature range 218---530^∘{}C. The activation energy and volume at the melting temperature and atmospheric pressure are, respectively, ΔH=5.6±0.5 kcal/mole and ΔVV₀=0.04±0.03. The pressure and temperature coefficients of the activation volume, although quite uncertain, were also determined. The small activation energy and volume indicate that copper diffuses in lead primarily by the interstitial mechanism.