Microstructure and tribological properties of laser-cladded TiC /TiAl composite coatings on TC4 alloy

In this study, TiC/TiAl composite coatings are prepared on TC4 substrate via laser cladding. The effect of TiC content (5, 10, 15, and 20 vol%) on the microstructure, microhardness, and wear characteristics of the coatings are investigated. The results show that the physical phases in all four coatings are mainly TiAl, Ti3Al, TiC, and Ti2AlC. The amount of rod-shaped Ti2AlC increases and the TiC dendrite orientation is weakened and significantly refined with decreasing TiC content. The hardness of the four coatings is 1.8–2.4 times that of the substrate, with the 15 vol% coating being the hardest (799 HV1.0). The wear rate of the 5 vol% coating is the lowest, 1.6 times lower than that of the substrate. This is mainly attributed to the heterogeneous structure of the coating composed of Ti-Al substrate, hard TiC particles, and self-lubricating Ti2AlC phase. The surface energy of the 5 vol% coating is the lowest, resulting in a very slight material migration from the wear surface, and the wear mechanism is micro-cutting.