Ceramics fiber reinforced composites are expected to be potential candidates as fusion reactor structural materials. Aluminum matrix composites reinforced with C or SiC fibers are investigated. The objectives of this investigation are to evaluate potential of Al matrix composites as low activation fusion reactor materials and to develop them for fusion applications. Mechanical properties were measured by three point bending test and mini size specimen tensile test for composite materials and mono-filament tensile test. Microstructure was inspected by means of SEM and TEM. The effects of radiation were studied using fission neutrons of JOYO(FBR) and JMTR(BWR) and 1 MeV electrons from a HVEM. Al matrix composites showed excellent stability under irradiation up to a certain fluence, named threshold fluence. For SiC fibers in the composites, increment of tensile strength and Young\u27s modulus and crystallization of amorphous SiC were observed below the threshold fluence. But at above the threshold fluence, strength drastically dropped. Alloying of Ni and Si to matrix aluminum alloys was suggested to be unfavorable for SiC/Al composite materials used under nuclear reactor environments
