Rheology and ultrasonic properties of metallic glass-forming liquids

摘要

The flow of metallic glass-forming liquids can be modeled as configurational hopping between inherent states across energy barriers that are assumed to be on average sinusoidal. Such treatment gives rise to a functional relation between viscosity and isoconfigurational shear modulus, which leads to a rheological law capable of effectively simulating the Newtonian and non-Newtonian viscosity of metallic glass-forming liquids over a broad range of fragility. High-frequency ultrasonic data gathered within the supercooled liquid region are shown to correlate well with rheological data, thus confirming the validity of the proposed treatment. Variations in shear modulus induced either by thermal excitation or mechanical deformation are correlated to variations in the measured stored enthalpy, suggesting that the elastic softening of these materials is govern by a unique functional relation between shear modulus and configurational potential energy.