High temperature ion-irradiation effects on microstructural evolution in β-SiC

High temperature and high dose irradiation effects on microstructural evolution in high purity β-SiC was studied by Single- and dual-ion irradiation, where 5.1 MeV Si²⁺-ions for displacement damage and 1 MeV He⁺ ions for (n, α) simulation were implanted at 1673 K. From a cross-sectional transmission electron microscopy (XTEM) study of the β-SiC irradiated with single-ion up to a dose of 100 dpa, high density dislocation loops were observed. Sizes and concentrations of the loops are dependant on displacement damage level. In the dual-ion irradiated specimen, dislocation network was observed through the dual-ion irradiated region At the same time, cavities were formed in both the grain and grain boundary. In front of the irradiated surface, localized growth of the cavities was observed. TEM micrographs demonstrate that the helium had a large mobility on grain boundary and dislocation network under high temperature irradiation. It is clarified that helium largely contributes to the development of irradiation-induced microstructural defects. The formation mechanisms of microstructural defects were also discussed.