Laser Cladding of a Ti–Zr–Mo–Ta–Nb–B Composite Coating on Ti60 Alloy to Improve Wear Resistance

To improve the wear resistance of the Ti60 alloy, laser cladding was used to obtain a composite coating containing a high-entropy (Ti0.2Zr0.2Mo0.2Ta0.2Nb0.2)B2 boride phase, with Ti, Zr, Mo, Ta, Nb, and B powders as the raw materials. The microstructure and wear characteristics of the coating were studied using XRD, SEM, EDS, and the pin-on-disc friction wear technique. The results show that the coating mainly consists of six phases: (Ti0.2Zr0.2Mo0.2Ta0.2Nb0.2)B2, ZrB2, TiB, TiZr, Ti1.83 Zr0.17, and Ti0.67Zr0.67Nb0.67. The average microhardness of the coating was 1062.9 HV0.1 due to the occurrence of the high-entropy, high-hardness (Ti0.2Zr0.2Mo0.2Ta0.2Nb0.2)B2 boride phase, which was about 2.9 times that of the Ti60 alloy substrate. The coating significantly improved the wear resistance of the Ti60 alloy substrate, and the mass wear rate was about 1/11 that of the Ti60 alloy substrate. The main types of wear affecting the coating were abrasive, adhesive, and oxidation wear, while the main wear affecting the Ti60 alloy matrix was abrasive wear, accompanied by a small amount of adhesive and oxidation wear.