RADIATION-INDUCED MICROSTRUCTURAL EVOLUTION IN SIC/AL COMPOSITE-MATERIALS

Radiation effects on SiC/Al composite materials, reinforced with multifilament SiC long fibers (Nicalon), were investigated using fission neutrons, electrons and Ni ions. Mechanical property changes by displacement damages were studied and were related to microstructural evolutions with special emphasis on interfacial structures. An increase of tensile strength and Young's modulus of SiC/Al composite was observed by fast neutron irradiation. The SiC fibers showed the same tendency also by mixed spectrum neutron irradiation, but hot-pressed composites degraded mainly due to the degradation in interfacial strength and to matrix hardening. X-ray diffraction analysis and TEM observations of Ni ion irradiated specimens indicated microcrystal formation in SiC fibers which improved material responses. In-situ observations in HVEM provided suppression of interfacial SiC crystal growth at elevated temperature, which is interpreted by another mechanism of radiation effect.