INTERDIFFUSION IN AMORPHOUS METALLIC ARTIFICIAL MULTILAYERS

Recent progress in the study of diffusion in amorphous metals using the artificial multilayer technique is reviewed. Two new preparation methods have been reported: in situ amorphization during deposition of elemental metals, and dual bath electrodeposition. Simultaneous measurements of densification and diffusivity have shown that diffusion is governed by density fluctuations that depend exponentially on the free volume. Diffusion is 30 to 150 times faster than is predicted from the Stokes-Einstein scaling of the viscosity. This can be explained if critical density fluctuations persist for many diffusional jumps before they collapse elastically.