Abnormal sub- Tg enthalpy relaxation in the CuZrAl metallic glasses far from equilibrium

Abstract

The sub- Tg enthalpy relaxation in glasses far from equilibrium (i.e., hyperquenched glasses) is usually manifested as a monotonic increase in both the onset temperature and the extent of enthalpy recovery with increasing the annealing temperature. Here we report an abnormal three-steplike relaxation pattern in hyperquenched Cu45 Zr45 Al10 and Cu48 Zr48 Al4 glasses below Tg, i.e., the usual monotonic increase is inverted when the annealing temperature increases to a critical value. This abnormal relaxation pattern could be attributed to the high extent of chemical heterogeneity in the CuZrAl supercooled liquids, and present a thermodynamic evidence for the dynamic fragile-to-strong transition in metallic glass-forming liquids. © 2011 American Institute of Physics.