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

• Published in: Optics and lasers in engineering Vol. 120; pp. 84 - 94
• Main Authors: Yanan, Liu, Ronglu, Sun, Wei, Niu, Tiangang, Zhang, Yiwen, Lei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2019
• Subjects: CeO2; Crack; Laser cladding; Microhardness; Microstructure; Wear properties; Wear properties; CeO2; Laser cladding; Microstructure; Microhardness; Crack
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2019.03.001

•Effect of CeO2 on cracking sensitivity of the laser cladding coatings on Ti811 were studied.•The addition of CeO2 can optimize the microstructure.•Excessive CeO2 can inhibit the precipitation of the secondary TiC phase.•The wear properties and microhardness of laser cladding coatings with proper amounts of CeO2 are observably improved. 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.