Grain boundary effects on chemical disorders and amorphization-induced swelling in 3C-SiC under high-temperature irradiation: From atomic simulation insight

High-temperature irradiation-induced amorphization in SiC is a crucial factor leading to swelling. This study employs atomistic simulations to clarify the effects of experimental irradiation damage (1.0 dpa) in polycrystalline 3C-SiC at 1000 K. The findings reveal amorphization and swelling thresholds at 0.45 dpa and 7.45 %, respectively. Interestingly, dose threshold for amorphization does not align with chemical bonding, volume swelling, or enthalpy thresholds. Instead, a competitive mechanism emerges between grain boundaries and the grain core in the evolution of chemical disorder and clusters. Moreover, as amorphization saturates and grain boundaries annihilate, the degradation of tensile strength and Young's modulus stabilizes at 21.1 GPa and 124.2 GPa, respectively. Notably, grain boundaries exert a significant influence on defect cluster formation during amorphous evolution and dominate the initial deterioration of mechanical properties at low damage doses. This study enhances our understanding of how grain boundaries and chemical disorder mechanisms impact amorphization SiC.