Effects of CeO2 on microstructure and properties of TiC/Ti2Ni reinforced Ti-based laser cladding composite coatings

Abstract

In this study, Ti-based composite coatings reinforced with TiC/Ti2Ni were fabricated on Ti811 titanium alloy surfaces by laser cladding TC4 + Ni60 mixed powders with different CeO2 contents (0, 1, 2, 3, and 4 wt.%). The effects of CeO2 addition on the phase composition, microstructure, microhardness, and wear properties of the coatings were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy (SEM), Vickers hardness testing, and friction wear testing. Cracks in the coatings were detected using the dye penetration method. The results showed that the coatings mainly comprised reinforced phases of TiC, Ti2Ni, TiB2, and the matrix α-Ti. Adding an appropriate amount of CeO2 could eliminate the “herringbone” cracks and improve the surface quality of the coatings. The morphology of the TiC phase changed from dendrites to particles and then to dendrites as the CeO2 content increased from 0 wt.%, 2 wt.% to 4 wt.%. CeO2 had a negligible effect on the phase compositions of the coatings but it significantly improved the microhardness and wear properties of the coatings, and the microstructure of the coating was refined by adding an appropriate amount of CeO2.