Thermodynamics and kinetics of Zr–Ti–Cu–Ni–Be bulk metallic glass forming liquids

The viscosity of the equilibrium melt as well as of the undercooled liquid of bulk metallic glass (BMG) forming Zr–Ti–Cu–Ni–Be alloys is several orders of magnitude higher than in pure metals and other alloys. The temperature dependence of the viscosity is consistent with that of a moderately strong liquid. Entropy, enthalpy and Gibbs free enthalpy of the supercooled liquids are closer to the crystalline mixture than in other alloys. Both, the sluggish kinetics and the relative thermodynamic stabilization are likely to have the same origin. The Zr–Ti–Cu–Ni–Be alloys are dense liquids with a small free volume and a pronounced tendency to develop short-range order. The viscosity can describe the crystallization kinetics at high temperatures, whereas at low temperatures it is controlled by solid like hopping of atoms.