Critical loading conditions of amorphization, phase transformation, and dilation cracking in 6H-silicon carbide

Amorphization, phase transformation, and dilation cracking are 3 major deformation/failure mechanisms of monocrystalline 6H-SiC. This paper studies their critical formation conditions and mechanisms under hydrostatic pressure and uniaxial compression and tension with the aid of large-scale molecular dynamics simulations. It was found that under hydrostatic pressure the major deformation mechanism is amorphization, that under uniaxial compression the major mechanism turns to phase transformation at low temperature and amorphization at high temperature, and that under uniaxial tension the dominating mechanism becomes dilation cracking. Increasing the temperature reduces the thresholds significantly and brings about a heterogeneous deformation mode. The study further concluded that these deformation mechanisms and their thresholds can be predicted theoretically.