Microstructure and property of composite coatings on titanium alloy deposited by laser cladding with Co42+TiN mixed powders

In this study, composite coatings were fabricated on Ti-6Al-4V alloy by laser cladding with Co42 Co-based self-fluxing alloy and TiN mixed powders. Microstructures and wear resistance of the cladding coatings with 20 wt% and 30 wt% TiN addition were investigated comparatively. The composite coatings were mainly comprised of γ-Co/Ni, CoTi, CoTi2, Co3Ti, NiTi, TiN, CrB, Cr7C3, TiC, TiB, and TiC0.3N0.7 phases. The composite phase components were beneficial to the improvement of the micro-hardness and wear resistance. Results showed that the micro-hardness of the composite coatings was 3-4 times the Ti-6Al-4V substrate and the wear resistance was enhanced as high as 18.2 times. With more TiN addition, the micro-hardness and wear resistance of the laser cladding coating were improved further. The microstructure, strengthening mechanism, and wear mechanism of the laser cladding coatings were investigated accordingly.