Deformation behaviors and mechanism of Ni–Co–Nb–Ta bulk metallic glasses with high strength and plasticity

A class of Ni–Co–Nb–Ta bulk metallic glasses (BMGs) with a high glass-forming ability is developed. With proper compositional modification, the BMGs exhibit the enhanced plastic strain (up to 4%) and the ultimate strength (up to 3540 MPa). It is found that the interactions of shear bands such as intersecting, arresting, and branching, which normally are related to the plastic metallic glasses, can be observed both in the plastic and brittle Ni–Co–Nb–Ta BMGs. Obvious serrated flow behavior is observed during plastic deformation. The origins of the plasticity and the serrated flow in the Ni-based BMGs are analyzed in analogy to that in crystalline materials.