Atomic study on deformation behavior and anisotropy effect of 3C-SiC under nanoindentation

3C silicon carbide (3C-SiC) has great potential and value for innovated high-precision devices. However, the high hardness make it a daunting task to understand its deformation behavior and anisotropy effect, which impedes its processing and application. In this study, we performed molecular dynamic simulations of nanoindentation to study the deformation behavior and anisotropy effect of 3C-SiC. It is found that the elastic deformation and incipient plastic deformation are orientation-dependent, exhibiting fourfold symmetry, central symmetry and threefold symmetry while indenting on 3C-SiC (010), (110) and (111) surfaces. The dislocations nucleate and propagate due to the high shear stress induced by indentation, which in turn leads to the dissipation of shear stress in the sample. In the plastic stage, the dislocations evolve from embryonic dislocations to ribbon dislocations, and finally to prismatic dislocations. The prismatic dislocation loops are surrounded by stacking faults in {111} planes, most of which are enclosed by four stair-rod dislocations in <110> orientations. Moreover, we find that Thompson tetrahedron is suitable for understanding the anisotropy effect of ceramics with cubic diamond structure, and it is applied to investigate the formation and evolution of dislocations systematically in 3C-SiC. This research is meaningful for understanding the deformation behavior and anisotropy effect of 3C-SiC. The results may provide theoretical support for the processing and application of 3C-SiC.