Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass*

A simple mean field model for avalanche behavior during quasistatic compressive deformation of a bulk metallic glass demonstrates that two distinct types of slip events occur during serrated plastic flow. These events are distinguished by their stress drop rate profiles. A symmetric stress drop rate profile characterizes the small serrations (with stress drop rates of 400-1000 MPa/s). These small slips correspond to the progressive or incremental propagation of a shear band. A sharply peaked stress drop rate profile characterizes the large slips (with stress drop rates of 1000-100,000 MPa/s). These large slips correspond to simultaneous shear with uniform sliding over the entire shear plane. Both small and large slip events occur throughout plastic deformation.