Reproducing the thermal effects induced by aging in La-based amorphous alloy

Physical aging intrinsically exists in amorphous materials and refers to the evolution of the nonequilibrium structure toward an equilibrium state. The aging process can significantly affect the thermomechanical properties of the amorphous materials, thereby influencing their macroscopic responses. Aging models not only help in understanding the underlying physical mechanisms of the relaxation behavior but also may provide an effective tool for predicting the physical and mechanical properties of metastable nonequilibrium materials in practical applications. In the current work, based on the measurement of calorimetric data and shear modulus during the heating process of amorphous metallic alloys, we obtained the mechanical and thermal property changes caused by physical aging. By incorporating the characteristic time of their α relaxation into a first-order kinetic equation and considering the coupled evolution between the characteristic time and the structural order parameter, we derived an aging kinetics model based on the hierarchically constrained atomic dynamics theory. This model effectively reproduces the thermal effects in the aging region and the supercooled liquid region observed in the calorimetric data.