THE EFFECT OF IRRADIATION ON THE STABILITY AND PROPERTIES OF MONOLITHIC SILICON-CARBIDE AND SICF SIC COMPOSITES UP TO 25 DPA/

Stability and properties of monolithic and SiCf/SiC composites were me asured before and after irradiation in a fast neutron spectrum up to 2 5 dpa between 500 and 1500 degrees C. Dimensional changes were relativ ely consistent with previous investigations. Strength and modulus of S iCf/SiC composites decreased after irradiation as a result of fiber/ma trix decoupling. For some composites, uniform elongation was not signi ficantly degraded by irradiation. Thermal conductivity also decreased after irradiation at low temperatures because of the introduction of l attice defects as phonon scattering sites. The retention of properties under the severe conditions of 25 dpa and 800 degrees C suggests that a composite tailored for neutron damage resistance can be developed.