A universal criterion for the failure threshold in slowly sheared bulk metallic glasses
Y. S. Luo, Zhongde Wang, J. Eckert, Junwei Qiao
Abstract
A theory, bridging the free-volume and shear-transformation zone concepts through mean field theory, is established to predict the failure threshold of bulk metallic glasses (BMGs), and the physical mechanism of slip is investigated. A linear relation between the increment of free-volume and strain rate at small time intervals is found to describe inhomogeneous flow. The room-temperature theoretical failure threshold, Smax, follows a universal material-dependent criterion Smax∼Tgη, where Tg is the glass-transition temperature and η is a constant related to the serrated flow. This criterion is in good accordance with experimental results and provides a quantitative understanding of the failure mechanisms highly dependent on the serrations in BMGs, which is helpful to enhance plasticity via tuning the failure threshold.