Microstructures and properties of TiN reinforced Co-based composite coatings modified with Y2O3 by laser cladding on Ti–6Al–4V alloy

Abstract In this study, TiN reinforced composite coatings were fabricated on Ti–6Al–4V substrate by laser cladding with Co42 self-fluxing alloy, TiN and Y 2 O 3 mixed powders. Microstructures and wear resistance of the cladding coatings with and without Y 2 O 3 addition were investigated comparatively. Results showed that the coatings were mainly comprised of γ-Co/Ni, TiN, CoTi, CoTi 2 , NiTi, TiC, Cr 7 C 3 , TiB, Ti 5 Si 3 and TiC 0.3 N 0.7 phases. The coatings showed metallurgical bonding free of pores and cracks with the substrate. Compared with the Ti–6Al–4V substrate, the microhardness and wear resistance of the coatings was enhanced by 3–4 times and 9.5–11.9 times, respectively. With 1.0 wt.% Y 2 O 3 addition, the microstructure of the coating was refined significantly, and the microhardness and dry sliding wear resistance were enhanced further. The effects of Y 2 O 3 were attributed to the residual Y 2 O 3 and decomposed Y atoms.