New Titanium Alloy Design And Irradiation Damage Effect Study For Nuclear Energy Applications

Most conventional titanium alloys contain nuclides with long half-lives,which are not conducive to the recycling of nuclear reactor structural materials after service,and conventional alpha titanium alloys have too low tensile and yield strengths to be used in nuclear reactors.In order to safely and effectively recycle the material components of nuclear reactors after service,a titanium alloy material with rapid radioactive decay induction,high strength,corrosion resistance and resistance to irradiation swelling must be developed.In this paper,a new near-αtitanium alloy material for nuclear reactor pressure vessel components was designed and investigated,and the microstructural evolution of the low-activation Ti-Ta-V alloy was studied by electron backscatter diffraction(EBSD),X-ray diffraction(XRD)and scanning electron microscopy(SEM).Irradiation behavior was investigated in detail by atomic force microscopy(AFM)and grazing incidence X-ray diffraction(GIXRD)techniques.Finally,the evolution mechanism of the displacement cascade collisions of the low-activation Ti-Ta-V alloy and CPTi was investigated in detail by molecular dynamics simulations.The main conclusions are as follows:Based on the JMat Pro software,a titanium alloy with the addition of low activation elements Ta and V was designed,and the Ti-Ta-V alloy was prepared by vacuum non-self-consuming arc melting.After rolling and heat treatment,the physical phase structure remained α-Ti and no phase transformation occurred.The incorporation of elements with different atomic radii led to lattice distortion,reduction of lattice constant and reduction of crystalline surface spacing.Compared with CP-Ti,the lattice distortion and solid solution strengthening resulted in a significantly stronger and tougher Ti-Ta-V alloy with good corrosion resistance in 3.5 % Na Cl solution.The irradiation swelling height of Ti-Ta-V alloy was found to be significantly lower compared to CP-Ti by atomic force microscopy(AFM)technique,indicating that the irradiation swelling of Ti-Ta-V alloy with added Ta and V atoms was significantly suppressed under room temperature He ion irradiation conditions.The Ti-Ta-V alloy did not produce a second phase in the physical phase before and after irradiation,but both lattice parameters became smaller,as obtained by grazing incidence X-ray diffraction.Due to the difference in the size of Ta and V atoms and the size of the matrix atom(Ti),lattice distortion was produced,which enhanced the compounding of vacancies and interstitial atoms,reduced the mobility of vacancies,and inhibited the growth of vacancies,thus reducing the irradiation swelling height.Moreover,a large number of large-sized helium bubbles were not formed,and the results indicate that the Ti-Ta-V alloy has good irradiation resistance under He ion irradiation conditions.Molecular dynamics(MD)simulations investigated the irradiation behavior and cascade collisions,and the Ti-Ta-V alloy produced a small number of stable defects with smaller cluster size and density compared to CP-Ti.The absorption of defects produced by cascade collisions by Ta and V elements with different size atoms indicates that the Ti-Ta-V alloy has good resistance to irradiation,which is consistent with the experimental results of He ion irradiation.In conclusion,Ti-Ta-V alloy is expected to be a new titanium alloy for nuclear reactor applications,which provides new ideas for the selection and optimization of low activation and radiation resistant nuclear materials.