Large-scale atomistic simulations of nanoindentation and crack propagation under compression

Large-scale molecular dynamics (MD) simulations have been performed on parallel computers to study nanoindentation-induced amorphization in silicon carbide crystal. The load-displacement response exhibits an elastic shoulder followed by a plastic regime consisting of a series of load drops. Analyses of bond angles, local pressure and shear stress, and shortest-path rings show that these load drops are related to dislocation activities under the indenter. We have found that amorphization is driven by the coalescence of dislocation loops and that there is a strong correlation between load-displacement response and ring distribution. Current efforts focus on large-scale MD simulations of (a) nanoindentation in amorphous and nanophase SiC and (b) crack propagation in amorphous and nanostructured SiO/sub 2/ under compression.