Thermal annealing of shear bands in deformed metallic glasses: Recovery mechanisms in Cu64Zr36 studied by molecular dynamics simulations

Molecular dynamics simulations on the recovery of shear bands in deformed binary Cu64Zr36 glasses are presented. While the shear band (SB) formation induced by plastic deformation leads to an increase in excess volume, the material surrounding the SB experiences a compressive strain due to the dilatation of the SB. This is accompanied by changes in topological and chemical short-range order within the shear band. Isothermal annealing of the sample leads to redistribution and annihilation of excess volume, which is coupled to the recovery of local order and depends on the temperature. At lower temperatures (500 K) diffusion by a chain-like process is the dominating mechanism of structural recovery, similar to processes occurring in supercooled liquids. At higher temperatures (800 K) individual atomic displacements also start to contribute to the recovery process. At temperatures close to the glass transition, the recovery occurs on timescales of about 20 ns. If the annealing temperature is higher than Tg, thermal activation is sufficient to rejuvenate the glass structure.