A MODEL OF NEUTRON IRRADIATION EMBRITTLEMENT FOR METALS

Irradiation embrittlement of metals is very important in the field of nuclear energy safety. In order to describe the irradiation embrittlement behavior of metals, a neutron irradiation embrittlement model for annealed metals was proposed based on Johnson-Cook constitutive model. The fracture true stress of the irradiated samples was taken as the same as the unirradiated sample. This model can predict the whole true stress-strain curve, and the fracture true strain of the irradiated annealed materials by using the yield strength only. The tensile true stress-strain curves, the fracture true stress, and the fracture true strain of high-purity aluminum with different doses were measured by quasi-static tensile tests. The results showed that a higher dose results in a higher yield strength and a lower fracture true strain. However, the fracture true stress is almost unchangeable. The size and number density of irradiation-induced defects for high-purity aluminum with different doses were mearsured by TEM microscope. The results showed that a higher dose results in a higher size and a higher number density of voids, but the size and the number density of dislocation loops were difficult to measure accurately due to their size and number density are too small. The parameters of this model were fitted by experimental data of high-purity aluminum, and the application effect of this model was checked. The predicted results of this model agree well with the experimental data, regardless wtether the yield was obtained by quasi-static tensile tests or by the size and number density of irradiation-induced defects. The critical irradiation dose of annealed high-purity aluminum predicted by this model also agrees well with literature.