SLOW MOTION IN A METALLIC LIQUID

Liquid ${\mathrm{Zr}}_{46.8}{\mathrm{Ti}}_{8.2}{\mathrm{Cu}}_{7.5}{\mathrm{Ni}}_{10}{\mathrm{Be}}_{27.5}$ has been studied by quasielastic neutron scattering. The microscopic dynamics of this bulk glass forming alloy deviates qualitatively from simple metallic liquids; it shows two-step structural relaxation like other liquids in their supercooled state. Unexpectedly for a nonfragile system, fast $\ensuremath{\beta}$ relaxation is in full accord with the mode-coupling theory of the liquid to glass transition. The long-time $\ensuremath{\alpha}$ relaxation suggests failure of the Stokes-Einstein relation.