CHEMICAL INTERDIFFUSION IN AMORPHOUS EARLY-LATE TRANSITION-METAL ALLOYS

This short review attempts to give a state-of-the-art summary of chemical interdiffusion in amorphous early-late transition metal alloys. Interdiffusion is essential for an understanding of most solid-state reactions, for example solid-state amorphization and the most common types of crystallization. Proposed models and mechanisms of diffusion in amorphous metallic alloys are summarized and compared critically with experimental results. The thermodynamic influence on chemical interdiffusion is described with special emphasis on the strong enhancement of interdiffusion in amorphous alloys with a large negative enthalpy of mixing. Interdiffusion in binary amorphous alloys, in which one of the atomic species is essentially immobile, has been observed to give rise to special effects such as difficulty for the amorphous solid to remain in a glassy state close to internal equilibrium during changes in composition and the formation of local stress fields, both of which may impede further interdiffusion.