Stacking-sequence-dependent plasticity and subsurface damage evolution in nanometric cutting of hexagonal SiC.

CONTEXT: Hexagonal SiC is a widely used third-generation semiconductor material that can be classified into several polytypes (2H, 4H, 6H and 8H) based on stacking sequence. Since crystal structure directly determines machinability, understanding the influence of stacking sequence is essential for optimising ultra-precision machining. In this study, abrasive scratching simulations were performed to systematically investigate the relationships among stacking structure, machinability and micro-slip behaviour. The results reveal that hexagonal SiC exhibits distinct fine slip behaviour, pronounced stacking-structure selectivity and local disorder characteristics, clarifying the differences in machinability across various polytypes.

METHODS: All simulations were performed using LAMMPS with the ABOP many-body potential to describe Si-C interactions. The abrasive was modelled as a deformable body with a negative rake angle of -35.5°. The SiC workpiece had an off-axis angle of 4° relative to the basal plane, with the C-plane (000-1) as the machined surface and scratching along the [01-10] direction. Simulation results were visualised and analysed using OVITO.