In situ observation of bending stress-deflection response of metallic glass

Understanding the shear banding mechanism is of significance not only for improving the mechanical performance of metallic glassy components but also for designing new metallic glassy materials with better combinations of strength and toughness. In this study, through an in situ bending experiment under a scanning electron microscope, the shear banding behavior and the bending stress-deflection response were investigated. We found that the flexural strength was higher than either the tensile strength or the compressive strength of the identical metallic glass. The initial appearance of shear bands was observed at a stress lower than the flexural yield strength. As shear band propagating stably, the flexural stress increases with increasing the deflection, which is similar to but analytically found different with the traditional “work-hardening” behavior of metallic crystalline materials. At the peak stress, a shear banding instability with an abrupt increment of plastic deformation localization and shear cracking was found. Some shear band zones were observed and the size of the zone in tension side of the bending sample was found larger than that in compression side.