Strain-hardening under uniaxial tension in a rejuvenated bulk metallic glass

A rejuvenated Zr-based bulk metallic glass is tested in tension: it shows strain-hardening and reaches 0.9% plastic strain at failure. The initial rate of increase of flow stress with strain is 73 GPa, much higher than normal for polycrystalline metals and alloys. This hardening rate and its decay with increasing strain are compared with published data on a representative range of conventional and novel alloys. Taking the onset of necking as failure, and using Considère's analysis, we conclude that the metallic glass, however much rejuvenated, is limited to tensile plastic strains of approximately 1%, because of the rapid decay of hardening rate with strain. Rejuvenation of the metallic glass blocks early catastrophic failure in a predominant shear orientation. In comparison with as-cast samples, the fracture surface of the rejuvenated sample is more rugged and the characteristic vein pattern is denser. The effects of rejuvenation on abrasive-wear behavior are also examined.