Effect of loading rate on failure in Zr-based bulk metallic glass

The uniaxial compressive behavior of Zr₃₈Ti₁₇Cu_10.5Co₁₂Be_22.5 bulk metallic glass was investigated over a wide strain rate range between 10^-4 and 10² s^-1 at room temperature. Fracture stress as well as strain was found to decrease with increasing strain rate. Specimens subjected to quasistatic loading developed mature shear bands and substantial plastic deformations, fracture surfaces were relatively smooth and revealed a well developed and uniformly distributed mixture of vein-like patterns and river-like patterns. The dynamically loaded specimens, on the other hand, fractured along one dominant shear band with relatively rough fracture surfaces, such as non-uniformly distributed vein-like patterns, micro shear bands, microcracks and liquid droplets. The experimental results demonstrate that the fracture behavior of the present bulk metallic glass is strongly affected by the strain rate. A negative strain rate sensitivity was found and discussed in detail.