The self-diffusivity of Be in the bulk metallic amorphous alloy ${\mathrm{Zr}}_{41.2}{\mathrm{Ti}}_{13.8}{\mathrm{Cu}}_{12.5}{\mathrm{Ni}}_{10}{\mathrm{Be}}_{22.5}$ is investigated. Below the glass transition temperature the data suggest a single atomic jump diffusion behavior of Be. By taking into account the change in configurational entropy due to the glass transition, we explain the mechanism for diffusion of Be in the supercooled liquid state (i.e., above the glass transition) of ${\mathrm{Zr}}_{41.2}{\mathrm{Ti}}_{13.8}{\mathrm{Ni}}_{10}{\mathrm{Cu}}_{12.5}{\mathrm{Be}}_{22.5}$ by single atomic jumps in a slowly changing configuration of neighboring atoms.

• Received 21 February 1995

DOI:https://doi.org/10.1103/PhysRevLett.75.2364