Relationship of deformation mode with strain-dependent shear transformation zone size in Cu-Zr metallic glasses using molecular dynamics simulations

Tensile behaviors of a Cu64Zr36 metallic glass (MG) at different deformation temperature and the strain-dependent average shear transformation zone (STZ) size in four Cu-Zr-based MG systems, have been investigated by molecular dynamics simulations. With increasing temperature, the transition from the localized deformation to the non-localized deformation indeed occurs in Cu64Zr36 MG. Within the condition applied here, the critical temperature is estimated to be 195 ± 5 K. The criterion for the temperature-induced deformation mode transition, was suggested, i.e., the competition between the elastic-energy density stored and the energy density needed for forming one mature shear band in MGs. We further reveal that for localized deformation in all studied cases, the average STZ size remains almost unchanged at strain larger than 14% while for non-localized deformation cases, after about 14% strain, the average STZ size continuously increases with strain up to 20% strain. This feature could be used to distinguish different deformation modes in MGs.