Shear Band Stability in Bending—Tension-Compression Asymmetry in Metallic Glass

Shear band stability is measured for a Zr-based bulk metallic glass in tensile and compressive bending. Different failure modes in bending are realized via beam geometry, using either rectangular or trapezoidal prisms. These characterizations are done at multiple fictive temperatures, revealing a compression-tension asymmetry in shear banding stability. Stability is higher in compression than tension at all measured fictive temperatures. This asymmetry suggests that shear band propagation is different in tension and compression, and possible mechanisms underlying this difference are suggested. Additionally, shear band stability, quantified in a critical stress gradient, is explored as a means of predicting plasticity in other testing geometries. The critical stress gradient measured in bending is shown to be consistent in uniaxial compression testing, demonstrating its potential for predicting a brittle vs. ductile response in different loading modes of bulk metallic glasses. Overall, our findings indicate that shear bands are more stable in compression than tension and offer a route towards predictive modeling of BMG deformation behavior.