Mechanical property changes and microstructures of iron irradiated with fission and fusion neutrons

Abstract

Mechanical property changes were observed for pure Fe irradiated with fission and fusion neutrons, and the irradiation-induced defect and deformation structures were correlated. Interstitial dislocation loops and voids were observed for specimens irradiated with both fusion and fission neutrons at temperatures higher than 563 K. The increase in the yield strength was well predicted from the number density, size and type of each defect for specimens irradiated at temperatures higher than 673 K with fission neutrons, while the observed increase in yield strength is larger than those observed for specimens irradiated at tempearatures lower than 573 K. These results show that the number of invisible defect clusters increases with decrease in irradiation temperature and is much larger in fusion neutron irradiation than fission neutron irradiation. From the increase in the yield strength, the number density of defect clusters was estimated by assuming their type and size.