Tensile plasticity in amorphous microwires: The role of ion irradiation-induced gradient rejuvenation

Abstract

Amorphous alloys possess exceptional mechanical properties such as high strength and elasticity but suffer from limited tensile plasticity at room temperature, categorizing them as quasi-brittle materials. Ion irradiation has emerged as a promising method for improving their plasticity by inducing gradient rejuvenation structures that modify the distribution of free volume. In this study, H⁺ irradiation was applied to amorphous microwires (AMs), introducing a nonlinear gradient rejuvenation structure with thickness of ∼1.76 μm, which features a free volume distribution that first increases to a certain depth and then decreases from the surface to the interior. It not only effectively hinders the propagation of the dominant shear band (SB) at the interface between high and low free volume regions but also promotes the formation and branching of numerous fine SBs within the rejuvenated region. The combination of these two effects results in significant enhancement of the tensile plasticity to ∼ 2.97 % while maintaining high yield strength (1680 MPa) of AMs. This outcome provides insights into the mechanisms enabling improved plasticity and highlights the potential of nonlinear gradient rejuvenation as a strategy to optimize the mechanical properties of bulk amorphous alloys, offering a promising pathway for developing next-generation high-performance metallic materials.