Structural anisotropic effect on the nanocutting of 6H-Silicon Carbide

6H-silicon carbide (6H-SiC) is an excellent material for fabricating die and high performance mirrors because of its desirable engineering properties such as ultrahigh strength and outstanding thermal and chemical stabilities. However, it is also a difficult-to-machine material due to its hardness, brittleness and anisotropy. This paper presents an investigation on the structural anisotropic effect on the nanocutting of 6H-SiC with the aid of large-scale molecular dynamics simulations. Six typical combinations of crystal planes and cutting directions were selected, i.e., (0001) < 1120 >, (0001) < 1100 >, (1120) < 1100 >, (1120) < 0001 >, (1100) < 0001 > and (1100) < 1120 > . The cutting-induced deformation morphology, deformation mechanism, depth of subsurface damage and elastic recovery were analysed and compared. It was found that the resultant deformation morphology changes significantly when the cutting was conducted under different conditions, suggesting a strong anisotropic effect. The depth of the subsurface damage varies from 2.64 nm ((0001) < 1100 >) to 5.66 nm ((1120) < 0001 >). Elastic recovery varies from 0.131 nm ((1100) < 1120 >) to 0.295 nm ((1120) < 0001 >). These are caused by the anisotropic effect on the nucleation of dislocations and phase transitions in the material. It was identified that the basal plane (0001) is the most machinable plane and the cutting on plane (0001) along < 1100 > is the most machinable crystal combination; while cutting on (1120) plane along <0001> direction gives the most unfavourable outcome.