Primary radiation damage in 3C-SiC under strain field studied with molecular dynamics simulation

Cubic silicon carbide (3C-SiC) has been selected as candidate structural and cladding materials for advanced nuclear systems due to its excellent properties. The influence of external mechanical load, thermal stress and radiation damage induced stress/strain field on radiation behavior in 3C-SiC is not well understood. In this work, the primary radiation damages in 3C-SiC under strain field have been investigated with molecular dynamics (MD) simulation. The results demonstrate that the strain field is of significant importance on the radiation damages in 3C-SiC. The threshold displacement energy decreases with strain from compression to tension. During displacement cascade and annealing, the surviving defect, defect clustered fraction and cluster size increase at the tensile state, while the defect recombination ratio decreases. Among the generated point defects, the vacancy and interstitial contribute to the majority of defect production increase under tensile strain. The higher energy of primary knock-on atom (PKA) results in more defect production but suffers from the same strain effect. High temperature increases the defect recombination ratio but reduces the surviving defect number during both displacement cascade and annealing process. Comparing with compressive state, tensile state exhibits a more significant temperature effect on defect production and recombination in displacement cascades, while a less significant temperature effect on defect cluster. All these results indicate that the influence of stress/strain state, especially tensile state, should be seriously taken into account for the application of SiC in nuclear reactor environment.