Helium release and diffusion mechanism in SiC containing B4C

Abstract Helium release measurement have been carried out in the temperature range of 750–1260 °C for neutron-irradiated α-SiC powder. The powders were obtained from SiC ceramics containing B 4 C with varying contents of 10 B, i.e., 4.2 × 10 16 , 1.13 × 10 17 and 1.84 × 10 17 atom/mg. Neutron irradiation was conducted up to a fluence of 2.8 × 10 24 n/m 2 ( E >0.1 MeV) at ∼300 °C. The diffusion coefficients were calculated for the temperature region of 750–1060 °C and for time intervals 0–10, 10–60 min and 1–6 h at each temperature. The diffusion coefficient of He for SiC was affected by the original 10 B concentration. Both helium diffusion coefficient and apparent activation energy were smaller for higher concentrations of 10 B.