Effect of crystal orientation and temperature on the mechanical properties and fracture mechanism of silicon carbide nanowires

Silicon carbide nanowires (SiC NWs) are widely used as reinforcing materials in composite materials based on ceramics, metals, and polymers, and their high-temperature mechanical properties have become a focus of attention. In this paper, the effect of temperature and crystal orientation on the tensile mechanical behavior of SiC NWs was explored through molecular dynamics simulation. It is observed that the fracture mode and mechanical properties of SiC NWs express a significant temperature dependence. Both critical stress and Young's modulus of nanowires with different orientations decrease with increasing temperature and the [111]- and [112]-oriented nanowires exhibit brittle fracture characteristics at low temperatures and become ductile fractures at high temperatures. The transition temperature for ductile–brittle fracture is between 1300-1800 K. The fracture surfaces of SiC NWs with different orientations are all {111} planes at low temperatures. This study provides theoretical support for SiC NWs' laboratory growth and toughening mechanism research.