Effect of structural anisotropy on the dislocation nucleation and evolution in 6H–SiC under nanoindentation

Single crystalline 6H–SiC possesses complex microstructure and its deformation is strongly anisotropic. With the aid of molecular dynamics analysis, this paper investigated the dislocation nucleation and evolution in 6H–SiC under nanoindentation on three major planes, i.e., (0001), (011¯0) and (21¯1¯0). It was found that the half loops of prismatic dislocations could form during the nanoindentation on the (0001)plane, while the prismatic dislocation loops emerged on the (011¯0) and (21¯1¯0)planes. Further analysis revealed that the half loops were generated via the interaction of the nucleated dislocations in the basal plane and the first prismatic planes {011¯0}; while the formation of the prismatic loops can be attributed to either the “lasso”-like mechanism or the combination of dislocation interaction and “lasso”-like mechanism. Such strong effect of structural anisotropy was clarified through the generalised stacking fault (GSF) energy surface and stress distribution.