Evolution of shear bands into cracks in metallic glasses

In the present work, the cracks formation and propagation behavior of a ductile Zr-based bulk metallic glass with single dominant shear band deformation was investigated. From the ideal compressive load-displacement curve of the sample with single shear band deformation, the instant at which the shear band turns into cracks and the total area of cracked-regions prior to failure were analyzed. Further investigations revealed that the micro-cracks might have originated from the local planar faults or defects within the shear plane along the shear direction. The existence of such planar faults (steps) was consistent with the observations of the surfaces of unfractured and fractured samples. Based on these results, a new interpretation of how shear bands evolve into the present micro-cracks was proposed. These novel results provide a new perspective to understand the deformation behavior of metallic glasses.