Microstructural evolution analysis of NITE SiC/SiC composite using TEM examination and dual-ion irradiation

Irradiation effects in a SiC/SiC composite reinforced by Tyranno-SA fibers and produced by an innovative processing method, nano-powder infiltration and transient eutectic phase (NITE) processing, were investigated. Dual-beam ion irradiation methods and energy-filtered transmission electron microscopy were used in the investigation. The NITE SiC matrix had dense, isotropic grains several hundreds nm in diameter. A small amount of secondary phases from residual additives were found within the SiC fiber bundles. Dual-ion irradiations achieved a dose of 60 dpa at 1200 °C. TEM investigation showed no significant modification by irradiation in either the Tyranno-SA fibers or the NITE SiC matrix, except for a small amount of micro-cavity formation. The synergistic effects of heavy irradiation and helium atoms in NITE SiC/SiC composites at elevated temperature are discussed.