Effect of displacement damage up to 50dpa on microstructural development in SiC/SiC composites

The effect of displacement damage up to 50 dpa on microstructural development in SiC/SiC composites with Hi-Nicalon Type S SiC fiber was investigated. He bubbles were observed in the matrix of SiC/SiC composites irradiated to more than 10 dpa in ion irradiations at 1000 °C. The average size of He bubbles increased with increasing displacement damage. Almost all the He bubbles were formed at the grain boundaries in the matrix irradiated to 10 dpa. On the other hand, He bubbles were also formed within the grains of the matrix irradiated to 50 dpa. The matrix irradiated to 50 dpa in a fusion reactor relevant condition had the largest average size of He bubbles. The average size of He bubbles in the matrix irradiated to 50 dpa decreased with increasing the amount of implanted H to more than a fusion reactor relevant condition. He bubbles were formed in fibers irradiated to more than 10 dpa.