Microstructure and Corrosion Properties of Ti2AlNb Irradiated by High Current Pulsed Electron Beam Treatment

Ti2AlNb alloy was treated with High Current Pulsed Electron Beam（HCPEB）. The microstructure of the alloy after irradiation was analyzed by X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy. The results showed that a large number of craters were formed on the surface after irradiation. The density of craters decreases significantly with the increase of irradiation times, and the alloy undergo α+β→O transformation after irradiation, the β and O phases are refined significantly. After irradiation, a remelting layer with a thickness of about 4μm was formed in the surface layer, and the aluminum in the remelting layer was supersaturated and formed an aluminum-rich layer. The irradiation produces high amplitude stress and temperature gradients in the subsurface layer, resulting in strong plastic deformation in the subsurface layer and the formation of high-density defect structures such as dislocation, twins and layer faults. The corrosion resistance of Ti2AlNb alloy is improved after irradiation, which is mainly attributed to the surface purification effect and composition homogenization after irradiation, the formation of dense Al₂O₃ protective film from the surface of aluminum-rich, and the enhanced diffusion of aluminum to repair the Al₂O₃ film lost in the corrosion process, which improves the corrosion resistance of Ti2AlNb alloy.