The Electron Irradiation Damage Of V-4Cr-4Ti Alloy

Vanadium-based alloys were considered as a kind of important candidate structural materials for future fusion reactor. In order to investigate the effects of electron irradiation on the microstructure in V-4Cr-4Ti alloy, electron irradiation was performed and microstructural evolution in V-4Cr-4Ti alloy had been in-situ observed using a high voltage transmission electron microscope (HVTEM) at293K and723K. For fully researching the effects of electron irradiation on the microstructure and mechanical property of V-4Cr-4Ti alloy, the rolled (at293K) and recrystallized (at1293K for1.5h) V-4Cr-4Ti alloys had ex-situ electron irradiated using an electron accelerator at440K. The mechanical properties of unirradiated and irradiated V-4Cr-4Ti alloys were investigated by Small Punch Test (SPT). The results showed that:The Ti-C-0precipitates of face-center-cubic (FCC) structure (a=0.4280nm) were not stable and dissociated during in-situ electron irradiation. The defect clusters formed and trapped irradiation-induced point defects to grow up with the further electron irradiation.In the V-4Cr-4Ti alloy, the growth rate (slope) of the defect clusters size for the doses (<0.5dpa) was larger than that for the doses (>1dpa). At723K, the growth rate and the defect clusters size in the V-4Cr-4Ti alloy were smaller than that in CLAM steel when the doses were above1dpa.The displacements to occur plastic deformation in the irradiated rolled and recrystallized V-4Cr-4Ti alloys were0.08mm and0.04mm smaller than that in the unirradiated alloys, respectively. This demonstrated that the ductility lost and plasticity reduced. The tensile strength of the irradiated V-4Cr-4Ti alloys increased with the irradiation dose increased, compared with unirradiated alloy. However, the irradiation dose dependence of the tensile strength of rolled V-4Cr-4Ti alloy was definitely different with that of recrystallized V-4Cr-4Ti alloy, because of their different microstructure. The fracture toughness increased in the irradiated rolled and recrystallized V-4Cr-4Ti alloys, compared with that in unirradiated alloy. And the increase trends had a good corresponding relation with that the tensile strength increasing trends. It meant that electron irradiation had more obvious impact on the tensile strength than the plasticity of V-4Cr-4Ti alloy. A lot of defect clusters formed and grow up with the irradiation dose increasing. And they hindered the dislocation enablement and movement. It was the reason for the electron irradiated V-4Cr-4Ti alloy plasticity to reduce, tensile strength to increase, and fracture toughness to increase.