Small atom diffusion and breakdown of the Stokes-Einstein relation in the supercooled liquid state of the Zr46.7Ti8.3CU7.5Ni10Be27.5 alloy

Be diffusivity data in the bulk metallic glass forming alloy Zr46.7Ti8.3Cu7.5Ni10Be27.5 are reported for temperatures between 530 and 710 K, extending 85 K into the supercooled liquid state of thr alloy, At the glass transition temperature T-g, a change in temperature dependence of the data is observed, and above T-g the diffusivity increases more quickly with temperature than below, The data in the supercooled liquid can be described by a modified Arrhenius expression based on a diffusion mechanism suggested earlier. The comparison with viscosity data in the supercooled liquid state of Zr46.7Ti8.3Cu7.5Ni10Be27.5 reveals a breakdown of the Stokes-Einstein relation, indicating a cooperative diffusion mechanism in the supercooled liquid state of Zr46.7Ti8.3Cu7.5Ni10Be27.5. (C) 1996 American Institute of Physics.