Insight from molecular dynamics into the phase boundary behavior and material removal mechanism during nanometric cutting of RB-SiC at various temperatures

This study used molecular dynamics (MD) simulations to systematically investigate the material removal mechanism of reaction-bonded silicon carbide (RB-SiC) during nanometric cutting at different temperatures, which fills the gap in understanding the material removal mechanism at the phase boundary of two-phase materials with mismatched properties. Results show that the strong mismatch in mechanical properties between the Si/SiC phase boundary produces a distinct soft-guidance effect caused by the hardness gradient i.e., amorphous structures preferentially flow along the phase boundary into the softer Si phase, leading to the V-shaped boundary defects pointing toward the Si phase. At elevated temperatures, the thermal softening effect becomes more pronounced, leading to a reduction in cutting forces by 32.2%. Moreover, the degree of amorphization in the SiC phase weakens, and the plastic deformation of Si phase increases, resulting in a more significant hardness-gradient soft-guidance effect at elevated temperatures. Overall, this work provides new theoretical insights into the unreported critical role of phase boundary of Si/SiC in RB-SiC.