Pinning effect on the correlations of nonaffine displacement in metallic glasses

We mimic the structural heterogeneity of inclusions in nanoscale by pinning a portion of atoms in CuZr metallic glasses (MGs) on molecular dynamics simulations with shear deformation. Results show yielding of the MGs transits from a system-spanning shear band (SB) to a localized plastic flow with pinning, due to the constrained length scale for the organization of the plastic events imposed by pinning. Spatial correlation of the nonaffine displacement exhibits a quadrupolar symmetry that shrinks with pinning, giving two characteristic lengths in the maximum and minimum directions that are both constrained by the static length for the pinned atoms. The two characteristic lengths signify the anisotropic nature of the plastic regions, which diminishes with pinning. These results shed light on the microscopic mechanism of tailoring the mechanical properties by tuning the static structure in MGs.