DIFFUSION IN THIN-FILM AMORPHOUS METALLIC ALLOYS

Due to their potential technological value and the interest from a bas ic scientific point of view, amorphous metallic alloys have been studi ed extensively in recent years. This includes investigations of atomic transport processes which play a key role for understanding, for exam ple, crystallization processes and the solid-state amorphization react ion. The first measurements of diffusion in amorphous alloys were carr ied out about two decades ago, being difficult because of crystallizat ion yielding very narrow temperature and time intervals in which the m easurements can be carried out. Such measurements have been made possi ble only with the development of ion beam analysis and sputter section ing techniques. A short summary of the experimental diffusion studies, mainly based on ion beam analysis, is given together with various the oretical models. These are based on defect-mediated diffusion and coll ective motion of many atoms. Nonconventional diffusion behavior caused , e.g., by buildup of stress during thermal annealing, relevant for so lid-state amorphization reactions, will be discussed, and studies of t he thermodynamic factor will be addressed.