Analysis of single-crystal 3C-SiC subsurface damage mechanisms based on molecular dynamics indentation speed

In order to explore the subsurface damage of single crystal 3C-SiC at different indentation speeds, molecular dynamics model of nanoindentation under a diamond indenter is constructed. The impact of varying indentation speeds on the formation of subsurface damage is thoroughly analyzed. Combining the diamond structure identification method and dislocation analysis, three indentation speeds of 50, 250, and 450 m/s are selected. From several perspectives, such as load–displacement curves, volumetric strain, atomic bond breaking, and dislocation evolution processes, the effect of different indentation speeds on the subsurface damage of single-crystal 3C-SiC is deeply investigated. When the indentation speed is 50 m/s, as the depth of the indentation increases, workpieces are more susceptible to elastic–plastic deformation under the action of external forces, and volumetric strain is significantly increased. At the indentation speed of 50 m/s, with a higher dislocation density, the atoms rearrange around the dislocation and more dislocation loops are formed. The atoms are also more closely arranged, and the local structure is more distorted. This leads to a high peak of C–Si in the radial distribution function, which reflects the irregularity of local atomic arrangement and the concentration of distribution. At the 50 m/s indentation speed, the elastic–plastic deformation of the workpiece leads to grain boundary stress concentration and damage. Grain evolution occurs with fractures and dislocations. The squeezing between atoms is strong, atomic bonds are broken and connected frequently, and subsurface damage is significant.