Structural Relaxation and Isoconfigurational Flow of a Metallic Glass Near Equilibrium.

The isoconfigurational viscosity of amorphous Pd77.5Cu6Si16 in various states of structural relaxation was investigated over a wide temperature range. It was found to be thermal history dependent and non-Arrhenian. The lower the glass fictive temperature, and hence the more ordered the glass, the greater the departure from Arrhenian behavior. The non-Arrhenian behavior shows that the temperature dependence of the isoconfigurational viscosity cannot be ascribed entirely to the temperature dependence of the jump frequency of the flow defect. The observed crossover of isoconfigurational curves obtained from different structural states implies that the isoconfigurational viscosity cannot be a function of only a single structural parameter, such as the average free volume of the specimen.