Molecular dynamics of shear transformation zones in metallic glasses

Molecular dynamics simulations have been employed to investigate the dynamics of atomic rearrangements in Ni50Zr50 amorphous alloys sheared at different pressures. Local atomic dynamics has been characterized in terms of number of displacing atoms as well as of apparent activation volume and energy. The dimensionality of rearranging atom clusters has been also evaluated. Numerical findings, although not conclusive, indicate that atomic rearrangements are probably triggered by a free volume redistribution. Highly localized and cooperative, such plastic rearrangements occur in regions tending to a two-dimensional occupancy of space.