Microstructural evolution and tribological properties of TC6 titanium alloy strengthened by laser peening combined with nitrogen ion implantation

To obtain a combined strengthening layer and further redouble the ability to resist wear of TC6 titanium alloy, an innovative technique of laser peening plus nitrogen ion implantation was proposed. The tribological properties of the specimen subjected to combined laser peening and nitrogen ion implantation were analyzed using transmission electron microscope, nanoindentation tester, sliding friction wear tester and scanning electron microscopy. The results showed that laser peening combined with nitrogen ion implantation induced a higher density of dislocation than that produced only by laser peening or nitrogen ion implantation. Compared with the ion implanted and laser peened samples, the surface nano-hardness subjected to combined strengthening process was increased by 21.3 % and 5.8 %. Moreover, the friction coefficient of combined processed specimen reduced to 0.4, the wear tracks depth and width were about 19.02 mu m and 300 mu m, while the wear mechanism was mainly abrasive and oxidative wear. The dislocations, sub-grains and mechanical twins produced by laser peening provided large amounts of diffusion channels for ion implantation, which conferred better wear resistance than the samples processed only by laser peening or nitrogen ion implantation.