Multimillion-atom nanoindentation simulation of crystalline silicon carbide: Orientation dependence and anisoiropic pileup

In this paper, we report multimillion-atom molecular dynamics simulations of nanoindentation on crystalline 3C-SiC surfaces: (110), (001), and (ill). The load-displacement responses of the three different indenting surfaces reveal a similar deformation mechanism at different indent depth. We have observed that dislocation activities in the indenting surfaces involves mutually repelling Shockley partial dislocations and the resulting extension of stacking faults during the expansion of dislocation loops. Detailed analysis shows that the estimated Peierls stress is 7.5GPa=3.9x102G, where G is the shear modulus. After the indenter is fully unloaded, we observe that the anisotropic pileup patterns lie on (111) and (111) slip planes. These patterns are closely related to dislocation activities on the two slip planes. The anisotropy reveals the asymmetry of the 3C-SiC crystal in which only (111) and (I 11) slip planes are active among the { 111) family. © 2007 Materials Research Society.