Shear banding and serrated flow behaviors of high toughness Zr61Ti2Cu25Al12 bulk metallic glass under bending

By interrupted three-point bending experiments, the detailed evolutions of shear-banding and serrated flow as well as their correlation of high toughness Zr61Ti2Cu25Al12 bulk metallic glass (BMG) under bending were systematically studied. Three stages can be classified during plastic bending of Zr61Ti2Cu25Al12 BMG based on the different characteristics of shear-banding and serrated flow behaviors. Moreover, there has a strong correlation between shear-banding and serrated flow at different stages of plastic bending. It is noteworthy that the driving force for shear bands propagation of BMG beam under bending depends on the bending moment, instead of the applied load. Thus, remarkable positive correlations among bending moment, shear band zone height and average load drop of serrations were found during plastic bending. During the progressive propagation of multiple shear bands, intense interactions and competitions among these shear bands have occurred, which manifested by the self-organized criticality behavior from serrated flow dynamics, as well as the very finer irregular striation patterns and uneven fluctuant morphologies which presented on the shear offset surface. The sizeable plastic zone of Zr61Ti2Cu25Al12 BMG is very favorable to achieve the greater macroscopic plasticity and lower the risk of fast catastrophic fracture. Thus, Zr61Ti2Cu25Al12 BMG is a promising engineering material for structure elements which are naturally subjected to bending load, such as compliant mechanisms and micro electromechanical systems.

Automated summary

The detailed evolutions of shear-banding and serrated flow and their correlation in Zr61Ti2Cu25Al12 bulk metallic glass under bending were systematically studied. Three stages were identified during plastic bending based on different shear-banding and serrated flow behaviors. The driving force for shear band propagation depended on the bending moment, and positive correlations were found between the bending moment, shear band zone height, and average load drop. Multiple shear bands exhibited intense interactions and competitions, and self-organized criticality behavior from serrated flow dynamics was observed.