A universal criterion for the failure threshold in slowly sheared bulk metallic glasses

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, S m a x, follows a universal material-dependent criterion S m a x similar to T g eta, where T g is the glass-transition temperature and eta 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.

Automated summary

This study establishes a theory bridging the free-volume and shear-transformation zone concepts to predict the failure threshold of bulk metallic glasses (BMGs) and investigates the physical mechanism of slip. The room-temperature theoretical failure threshold follows a material-dependent criterion similar to the glass-transition temperature, providing a quantitative understanding of failure mechanisms highly dependent on serrations in BMGs. The linear relation between the increment of free-volume and strain rate at small time intervals describes inhomogeneous flow.