Identifying the origin of strain rate sensitivity in a high entropy bulk metallic glass

A series of nanoindentation tests were performed on a high entropy bulk metallic glass (HE-BMG). At low peak-loads, high positive strain rate sensitivity was found. But increasing the peak-load, the sensitivity of hardness to strain rate decreased dramatically. At low peak-loads, sluggish diffusion in HE-BMG significantly impedes atomic arrangement in the shear yielding events, whereas at high peak-loads, the shear-band deformation is dominated by the shear front triggered events. The work showed the origin of strain rate sensitivity in HE-BMGs and might help for tailoring the mechanical properties.