Molecular dynamics studies of plastic deformation during silicon nanoindentation

Molecular dynamics studies are performed to investigate the evolution of the deformed region during nanoindentation of silicon. A new approach based on a local strain diagnostic to identify and characterize the plastic rearrangements occurring during indentation is presented. During indentation, the response of the substrate changes from elastic to plastic to relieve the accumulated stress. The plastic rearrangements involve the displacement of atoms from the lattice sites to interstitial sites. The formation of interstitials results in the transformation of the deformed region to a denser amorphous phase. During retraction of the tip, the deformed region undergoes an incomplete elastic recovery signifying the plastic nature of rearrangements.