Study of helium bubble formation in SiCf/PyC/β-SiC composites by dual-beam irradiation

Abstract The formation of helium bubbles in the advanced SiC composites, Tyranno-SA SiC/PyC/β-SiC (TSA) and Hi-Nicalon Type-S SiC/PyC/β-SiC (HNS), implanted with helium and irradiated by dual-beam was investigated. Post-implantation annealing was carried out at 1000/1200/1400 °C, and dual-beam irradiation at 800/1000 °C. For He implantation, helium bubbles were observed only in the SiC matrix for annealing temperatures ⩾1200 °C. For dual-beam irradiation, no He bubbles were observed for a dose of 10 dpa, but for doses up to 100 dpa, He bubbles were observed in the matrix. Under these irradiation conditions, the TSA and HNS fibers exhibited good microstructural stability against helium influence. In addition, possible diffusion modes were suggested here to describe the diffusion behavior of helium in SiC in different temperature regions.