Dynamic viscoelasticity of Zr-Al-Ni-Cu metallic glass in the glass transition region

Viscoelastic behaviour of a metallic glass Zr55Al10Ni5CU30 has been studied by measuring the dynamic shear modulus G under forced vibration at low frequencies below 1 Hz. In measurements with increasing temperature, the shear modulus falls markedly at temperatures around the glass transition but at different rates under different vibration frequencies. The dynamic viscosity eta has been evaluated using the relation eta = G/(i omega), where omega is the angular frequency. The curves of vertical bar eta vertical bar vs temperature of different frequencies converge to a single curve in the glass transition region, and the converged curve is in fair agreement with the data reported in the literature. The dynamic glass transition point, defined as the vibration frequency and temperature at which the curves of the storage modulus G(1) and the loss modulus G(2) cross each other, obeys the Arrhenius law. The pre-exponential factor and the activation energy of the transition frequency are unusually large, suggesting that collective movements of atoms control the transition. (C) 2009 Elsevier B.V. All rights reserved.