Shear fracture and fragmentation mechanisms of bulk metallic glasses

Zr- and Co-based bulk metallic glasses display completely different failure modes under compressive loading. Zr-based metallic glasses always fail in a pure shear mode, whereas Co-based metallic glasses often break into small particles or powder, exhibiting a fragmentation mode. The difference in the failure modes for the two glassy alloys indicates that different mechanisms control the fracture processes, which can be described by a combined effect of surface energy gamma, cleavage strength sigma(0), fragmentation coefficient F-n and fracture mode factor alpha = tau(0)/sigma(0).