Two-step relaxation in a viscous metallic liquid

We have studied the microscopic dynamics of the bulk glass forming alloy Zr 46.8Ti8.2Cu7.5Ni10Be27.5 with quasi-elastic neutron scattering. In contrast to simple metals the equilibrium liquid has a two-step structural relaxati on as do other liquids in their supercooled state. The fast beta-relaxation is in quantitative agreement with the scaling function of mode-coupling th eory, with a crossover temperature, T-c, some 50% greater than the caloric glass transition temperature. The longer time alpha-relaxation reveals a fa ilure of the Stokes-Einstein relation. (C) 1999 Elsevier Science B.V. All r ights reserved.