| Abstract Scope |
The influence of composition, cooling rate, temperature, and strain rate on tensile deformation of metallic glasses is investigated using large-scale molecular dynamics simulations. Increasing quenching rate, temperature or strain rate affect activation of shear transformation zones (STZs) and shear banding, causing a brittle-to-ductile transition. A quantitative interpretation for enhanced ductility is obtained by saddle point sampling on the potential energy surface. Although the glassy structure does not significantly change with temperature the kinetic energy of the atoms increases dramatically, thereby increasing the probability of thermal STZ activation. A large number of STZs is also activated by high strain rate deformation via storing large amounts of elastic energy in the glass. The high density of STZ events and complex percolation processes impede strain localization and formation of critical shear bands. These results provide an atomistic understanding for strain localization mechanisms in metallic glasses and shed light on the brittle-to-ductile transition. |