Expanding the homogeneous regime of deformation in bulk metallic glass by electromigration-induced rejuvenation

Abstract

AbstractThe origin of plasticity in bulk metallic glasses (BMGs) is highly elusive due to their complicated amorphous atomic structures. Nonetheless, there is a general consensus that the homogeneous regime of deformation on the deformation map of BMGs is constrained by high temperature and low strain rate. Here we report an expanded homogeneous regime in a Zr55Cu30Al10Ni5 BMG, which is achieved by applying a pulsed electric current to the BMG specimen subjected to external loading. The BMG specimen exhibits homogeneous elongation and necking, rather than shear banding as it should without pulsed current. The results indicate that the pulsed current produces an additional effective “temperature increment” ∼0.15Tg (Tg, the glass transition temperature) apart from the Joule heating effect. This expanded homogeneous regime is attributed primarily to electromigration-induced dynamic rejuvenation which promotes homogeneously distributed deformation by enlarging the shear transformation zones. These findings could benefit understandings of plasticity in glassy materials.