In situ mechanical characterization of Cu-Zr based metallic glass micropillars under varying strain rates

• Alloys at high strain rates have more shear band nucleation sites. • Low strain rates inhibit the generation of localized shear bands in the alloy. • At high compressive strain rates, the shear bands of the alloys show an inhomogeneous elongated distribution. • At low compressive strain rates, the alloys have a regular parallel distribution of thick and long shear bands. In this study, micropillar specimens were fabricated using focused ion beam (FIB) milling. The mechanical properties of these micropillars were systematically investigated through a combined approach incorporating in situ transmission electron microscopy (TEM) compression testing, scanning electron microscopy (SEM) observations, and molecular dynamics (MD) simulations under varying strain rate conditions. Our experimental results demonstrate that the deformation behavior is strongly strain-rate dependent: at high strain rates, the micropillars predominantly form small, randomly oriented shear zones, whereas at lower strain rates, they exhibit more uniform and elongated shear zones patterns accompanied by enhanced plastic deformation. Through atomic-scale MD simulations, we have elucidated the fundamental mechanisms underlying shear zones formation and evolution. These findings provide valuable insights into the strain-rate dependent deformation mechanisms of amorphous alloys and offer potential strategies for enhancing their plasticity through strain rate control.