The toughening mechanism and spatial–temporal evolution of shear bands at different strain rates in Vit-1 metallic glass

Abstract

Shear banding behavior plays an essential role in exploring the toughening mechanisms of bulk metallic glasses (BMGs). However, due to the instability in time and inhomogeneity in space, it is difficult to investigate the formation, extension, intersection and other spatial–temporal evolution of shear bands via the previous ex-situ method. In this work, uniaxial compressions for Zr41.2Ti13.8Ni10Cu12.5Be22.5 (Vit-1) BMGs are conducted at the strain rates of 3 × 10−5/s, 3 × 10−4/s, and 3 × 10−3/s. Multi-surface in-situ Digital Image Correlation (DIC) measurement is used to capture the spatial–temporal evolution of multiple shear bands, presenting results that cannot be found by the previous ex-situ method. The stick–slip behavior between multiple shear bands is directly observed. Based on the free volume theory, a quantitative calculating method coupled with stress and strain rate for local viscosity of metallic glass is proposed. The inhibiting mechanisms of shear band intersections on their further evolutions are discussed. Besides, the intersection of shear bands may not be the cause of toughening metallic glasses, which even make them more brittle when different atomic clusters are shearing in the same plane.