Microstructural development in cubic silicon carbide during irradiation at elevated temperatures

Microstructural development in chemically vapor-deposited (CVD) high-purity beta-SiC during neutron and self-ion irradiation at elevated temperatures was studied. The CVD SiC samples were examined by transmission electron microscopy following neutron irradiation to 4.5-7.7 × 10²⁵ n/m² (E > 0.1 MeV) at 300 and 800 °C and 5.1 MeV Si²⁺ ion irradiation up to ∼200 dpa at 600-1400 °C. The evolution of various irradiation-produced defects including black spot defects, dislocation loops, network dislocations, and cavities was characterized as a function of irradiation temperature and fluence. It was demonstrated that the black spot defects and small dislocation loops continue to dominate at relatively low temperatures (<∼800 °C), whereas they grow into Frank faulted loops and finally develop into dislocation networks at a higher temperature (1400 °C). Substantial cavity formation on grain boundaries and stacking faults was confirmed after ion irradiation at 1400 °C. These observations were discussed in relation with the known irradiation phenomena in SiC, such as low temperature swelling and cavity swelling.