Rate-dependent shear-band initiation in a metallic glass

A statistical analysis of the rate-dependent pop-in behavior during spherical nanoindentation of a metallic glass is presented. Since the first pop-in of a test corresponds to the initiation of plasticity, this method provides insights into the fundamentals of shear-banding behavior. In this study, test series with different applied loading rates reveal that the initiation of a shear band is thermally activated with a rate- and stress-dependent activation volume. We further find a spatial inhomogeneity of the elastic modulus at the micrometer scale. This long-range structural heterogeneity does not strongly correlate with the shear-band initiation stress.