Atomistic mechanisms of amorphization during nanoindentation of SiC: A molecular dynamics study

Atomistic mechanisms underlying the nanoindentation-induced amorphization in SiC crystal has been studied by molecular dynamics simulations on parallel computers. The calculated load-displacement curve consists of a series of load drops, corresponding to plastic deformation, in addition to a shoulder at a smaller displacement, which is fully reversible upon unloading. The peaks in the load-displacement curve are shown to reflect the crystalline structure and dislocation activities under the surface. The evolution of indentation damage and defect accumulation are also discussed in terms of bond angles, local pressure, local shear stress, and spatial rearrangements of atoms. These structural analyses reveal that the defect-stimulated growth and coalescence of dislocation loops are responsible for the crystalline-to-amorphous transition. The shortest-path-ring analysis is effectively employed to characterize nanoindentation-induced structural transformations and dislocation activities. © 2005 The American Physical Society.