Dynamic fracture behavior of Zr63Cu12Ni12Al10Nb3 metallic glass under high strain-rate loading

We investigate the fracture behavior of a Zr-based bulk metallic glass, Zr63Cu12Ni12Al10Nb3, subjected to quasi-static compression, dynamic compression and flyer-plate impact experiments. The metallic glasses yield once the stress reaches the critical value and subsequently premature fracture occurs in a brittle manner through shear bands expanding rapidly under uniaxial stress loading, leaving vein patterns, some of which evolves into dendrite-like patterns due to the increase of strain rate. For uniaxial strain loading, the equivalent stress is lower than critical stress and shear bands are suppressed. The fracture mechanisms are nucleation and coalescence of voids rather than shear bands evolution, exhibiting the typical fractography of ductile fracture with microvoids, dimples and cup-cone structures. Compared with quasi-static and dynamic compression, higher impact stress induced the reduction of available free volume under planar impact loading. In such a case, decohesion strength, as a key parameter which characters ductile fracture, becomes higher, resulting in change from shear banding to void coalescence under planar impact loading.