Diffusion in bulk metallic glasses

Abstract

Due to the simple structure, bulk metallic glasses are very convenient model systems for studying the mechanism of atom diffusion in disordered media. In this paper, we analyze literature data on diffusion for a set of atoms in the metallic alloy Zr 46.75 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 (Vitreloy 4) above and below the glass transition temperature. We show that the activation energy of diffusion, E, is controlled by the high-frequency shear modulus, G ∞, and can be presented in the form E = const × G ∞ in the whole temperature range studied. We conclude that the displacements of a group of atoms in metallic alloys occur during the elastic shear deformation of their surroundings. The diffusion mechanism is the same both in the glassy state and in the supercooled melt.