Volume and enthalpy relaxation in Zr55Cu30Ni5Al10 bulk metallic glass

The structural relaxation in a Zr55Cu30Ni5Al10 bulk metallic glass was investigated by volume and enthalpy relaxation at various temperatures. The relaxation kinetics was well described by a stretched exponential relaxation function, Phi(t) = exp[-(t/tau)(beta)]. The Kohlrausch index, beta, ranged from 0.35 to 0.69, while the temperature dependence of relaxation time, tau was best fitted by the Vogel-Fulcher-Tanmmann formula, tau(T) = tau(0) exp [D* T-0/(T - T-0)], with tau(0) = 1.1 x 10(-14) s, D* = 44.2 and T-0 = 311 K. Atomic volumes in the equilibrium liquid region were measured by the electrostatic levitation method and these volumes, together with volumes of relaxed glasses, were better described by the Cohen-Grest model than by the Cohen-Turnbull model. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.