Shear band initiation delayed by interfacial strain relaxation in a B2-CuZr-enhanced nano-metallic-glass-composite

Abstract

The macro-plasticity of metallic glasses (MGs) has long been limited by their intrinsic lack of dislocation-mediated plasticity and the pronounced tendency for strain to localize into narrow shear bands. Fracture in MGs typically initiates with the activation of a few localized shear events (i.e., shear transformation zones, STZs), followed by the aggregation of numerous STZs into embryonic primary shear bands, their subsequent propagation, and ultimately catastrophic failure. To conquer shear localization into narrow shear bands, various strategies have been developed, including alloying, rejuvenation, free volume modulation, shear band deflection, and transformation-induced plasticity, to increase homogeneous deformation. While strain engineering is widely recognized and applied in two-dimensional materials to modulate lattice and band structures for tuning physical properties, it has been rarely explored to improve the deformability of crystalline–amorphous composites. In this work, molecular dynamics simulations demonstrate that incorporating B2 austenite into the amorphous matrix nearly doubles the strain range of the elastic–plastic deformation stage of the amorphous matrix and significantly delays the coalescence of STZs, thereby effectively enhancing the deformation capability of the monolithic amorphous alloy. These findings demonstrate an effective interfacial strain engineering strategy to stabilize early plasticity in metallic glass-based alloys.