A study of deformation behavior and phase transformation in 4H-SiC during nanoindentation process via molecular dynamics simulation

The deformation behavior and phase transformation of 4H silicon carbide (4H-SiC) during nanoindentation process is investigated with a cube corner diamond indenter through molecular dynamics simulation. It is found through the research that the basal dislocations are most likely to be generated in (0001) face and the indentation process contributes to the distortion of 4H-SiC lattice. In addition, phase transformation from 4H-SiC to 3C-SiC is firstly observed via MD simulations during indentation process. Cross-sectional observation in (1 (2) over bar 10) plain shows that 3C-SiC layers appear firstly during nanoindentation process, and the layers are observed at small indentation depth. 3C-SiC grain is generated based on 3C-SiC layers, and the transformation is more likely to appear at larger indentation depth. The phase transformation from 4H-SiC to 3C-SiC results from the shear stress induced by indenter during loading process. 3C-SiC grain and layers are both generated from the slip of 3C seeds under the influence of shear stress, and the condition of 3C-SiC grain formation is stricter. Moreover, the P-h curve is studied and the vertical deformation mode during indentation process on 4H-SiC can be reflected on P-h curve as small pop-in events. The findings are meaningful for the study of deformation mechanism of SiC and the application of SiC in precision machining.