Effect of Strain Rate and Extrinsic SIZE Effect on Micro-Mechanical Properties of Zr-Based Bulk Metallic Glass

Abstract

In this study, the mechanical properties and deformation features of Zr-based bulk metallic glass (BMG) are investigated at micro-scale via in situ micro-pillar compression. Furthermore, the effects of the strain rate and micro-pillar diameter on respective stress–strain curves are investigated. Together with the mechanical properties, such unique in situ micro-pillar compression techniques provide physical status to the micro-pillars, referring to the instances of stress–strain curves. It is noted that the effect of the strain rate on the stress–strain behaviour of the BMG diminishes with increasing micro-pillar diameter. In contrast, yield and ultimate compressive strength increase with increasing micro-pillar diameter, up to 4 µm. The deformation details after compression, as a result of conformed mechanical loading, are analysed by SEM and TEM. As evident from electron microscopy investigation, the plastic deformation is evidenced by the presence of multiple slip/shear bands, acting as load accommodation mechanisms in the course of mechanical loading together and resemble local plastic flow (ductile in nature) between two shear plans.