Study of subsurface damage during nano-grinding of B3-GaN using molecular dynamics simulations

The mechanism of subsurface damage formation during zinc blende gallium nitride (B3-GaN) nano-grinding was investigated using molecular dynamics (MD). The effects of grinding depth and abrasive radius on the grinding force, temperature, potential energy, phase transition, dislocations, the average coefficient of friction (COF), material removal rate (MRR) and subsurface damage were systematically investigated. The results show that dislocations, amorphization and wurtzite (B4) phase transitions are the primary defects present in the subsurface damage layer. Dislocation nucleation and proliferation are the main mechanisms aggravating the subsurface damage, and the 1/2<110> perfect dislocation along the <110> slip direction predominates in the dislocation. Grinding forces, temperature, potential energy, amorphous atoms, B4 phase atoms and dislocations increase with increasing grinding depth, exacerbating the subsurface damage of B3-GaN. As the abrasive radius increases, the amorphous atoms increase and then decrease, with the B4 phase atoms gradually reducing. The rest of the above parameters increase gradually, exacerbating the subsurface damage of B3-GaN. Furthermore, a smaller grinding depth and abrasive radius result in better machining accuracy, but decrease MRR. A technical reference for the ultra-precise and low-damage processing of B3-GaN can be provided by this study.