Microscopic and macroscopic properties of diffusion in metallic glasses

In this article, we review the current state of knowledge of atomic diffusion in metallic glasses. In the first part, we analyse the available experimental data, putting a particular emphasis on the coherence of the results obtained in different laboratories and for different amorphous systems. We show that the available results contain probably still unreliable data, a conclusion which could in part explain the correlation between pre-exponential terms and activation energies sometimes observed. In the second part, we present briefly the main characteristics of random walk in a random medium, as a statistical model of diffusion in glasses valid at least for a defect mechanism. Finally, we analyse the atomic mechanisms proposed up to now for diffusion, underlining the studies remaining to be done before a valuable comparison with experimental results can be done.