TEMPERATURE AND PRESSURE-DEPENDENCE OF GE DIFFUSION IN ALUMINUM

Results on the temperature and pressure dependence of Ge diffusion in pure aluminium are reported. Radiotracer methods in combination with serial sectioning by microtome are employed in our experiments. Oxide field-up effects are avoided either by ion implantation of Ge-71 or by sputter-cleaning of the aluminium samples prior to evaporation of a thin Ge-71 layer. Ge is a normal diffuser in aluminium with an activation enthalpy of 119.4kJ/mol and a pre-exponential factor of 3.39 x 10(-5) m(2) s(-1). The activation volumes (1.16 Ohm at 763 K, 1.24 Ohm at 841 K; Ohm denotes the atomic volume) indicate that Ge diffusion proceeds via vacancies. The results are discussed together with work on several other solute diffusers with emphasis on recent studies from our laboratory.