Effects of neutron irradiation on fine structure and strength of sic fibers

Abstract

Two types of SiC fibers, amorphous SiC(1000) (heat-treated at 1000°C) and microcrystalline SiC(1300) (heat-treated at 1300°C), were neutron-irradiated at 423 K to 8 × 10 23 and 2 × 10 24 n/m 2 , and at 923 K to 9 × 10 24 n/m 2 in JMTR ( E > 1 MeV). In the 423 K irradiation, density increased and X-ray radial distribution function (RDF) indicated that the atomic arrangement of SiC(1000) scarcely changed and that of SiC(1300) was disordered. Tensile strength and Young's modulus gradually increased with neutron fluences. In the 923 K irradiation, density increased and RDF indicated that the atomic arrangement of SiC(1300) scarcely changed and that of SiC(1000) was ordered. Young's moduli of SiC(1000) and SiC(1300) greatly increased. There were differences in density, tensile strength and Young's modulus between SiC(1000) and SiC(1300) before the irradiation, but their values became almost the same by the irradiation at 423 K to 2 × 10 24 n/m 2 and 923 K to 9 × 10 24 n/m 2 , respectively.