Radiation resistivity of Ti-5331 alloy with different microstructures

Titanium alloys have promising potential for applications in marine nuclear power systems owing to their exceptional mechanical and corrosion properties. Nevertheless, their radiation resistivity is a determining factor for their extensive use as structural materials in nuclear energy systems. In this study, the radiation resistivity of Ti–5Al–3V–3Zr–Cr (Ti-5331) alloys with three different microstructures was examined using a combination of characterization techniques including positron annihilation Doppler broadening spectroscopy (DBS), Elastic Recoil Detection Analysis (ERDA), Transmission Electron Microscope (TEM), Small-Angle X-ray scattering (SAXS) and nanoindentation. The results reveal that the equiaxed structure, bimodal structure, and Widmanstatten structure of Ti-5331 alloy obtained through different annealing processes exhibit differences in the number of interfaces and the content of the β phase. The α/β interfaces can significantly enhance the radiation resistance of titanium alloys by inhibiting the diffusion of helium atoms after helium ion irradiation. Notably, the alloy with a bimodal structure exhibited the best overall radiation resistivity, showing small defect size, low hardening effect, and low swelling rate of 0.003%. Moreover, the size of helium bubbles of the bimodal structure is half of that in the equiaxed structure and Widmanstatten structure. Thus, the bimodal structure of the Ti-5331 alloy possesses superior radiation resistivity.