Mechanical behavior of silicon carbide nanoparticles under uniaxial compression

The mechanical behavior of SiC nanoparticles under uniaxial compression was investigated using an atomic-level compression simulation technique. The results revealed that the mechanical deformation of SiC nanocrystals is highly dependent on compression orientation, particle size, and temperature. A structural transformation from the original zinc-blende to a rock-salt phase is identified for SiC nanoparticles compressed along the [001] direction at low temperature. However, the rock-salt phase is not observed for SiC nanoparticles compressed along the [110] and [111] directions irrespective of size and temperature. The high-pressure-generated rock-salt phase strongly affects the mechanical behavior of the nanoparticles, including their hardness and deformation process. The hardness of [001]-compressed nanoparticles decreases monotonically as their size increases, different from that of [110] and [111]-compressed nanoparticles, which reaches a maximal value at a critical size and then decreases. Additionally, a temperature-dependent mechanical response was observed for all simulated SiC nanoparticles regardless of compression orientation and size. Interestingly, the hardness of SiC nanocrystals with a diameter of 8 nm compressed in [001]-orientation undergoes a steep decrease at 0.1–200 K and then a gradual decline from 250 to 1500 K. This trend can be attributed to different deformation mechanisms related to phase transformation and dislocations. Our results will be useful for practical applications of SiC nanoparticles under high pressure.