Temperature dependence of serrated flow, strain-rate sensitivity and activation volume in a Ti-based bulk metallic glass

Abstract

In this study, the influence of temperature on serrated flow behavior, strain rate sensitivity (SRS) and effective activation volume in a Ti-based bulk metallic glass (BMG) bent at different strain rates has been investigated. Results reveal that the fundamental origin of shear deformation is related to the time-dependent structural relaxations, which occur during deformation at special temperatures and strain rates. Furthermore, the localized structural relaxation processes at intermediate temperatures cause an inelastic shuffling within cages and mitigate the activation of STZs. The main reason of negative SRS at intermediate temperatures is due to the insufficient time for structural relaxation at high strain rates, which leads to a larger free volume concentration within shear bands and makes the BMG softer. It is concluded that the activation volume increases with temperature in the inhomogeneous deformation region, whilst its value at high temperatures, where the deformation regime is homogeneous, decreases with temperature rise.