Tribological behavior of diamond reinforced FeNiCoCrTi0.5 carbonized high-entropy alloy coating

(FeNiCoCrTi0.5)Cx (x = 3 wt%, 6 wt%, 12 wt%) carbonized high-entropy alloy-based composite coatings, marked as C3, C6 and C12, were prepared on 45 steel by laser cladding. The macroscopic morphology, phase, microstructure, hardness and wear resistance of coatings have been investigated systematically. The results indicate that diamond content has a significant influence on the microstructure and mechanical properties of (FeNiCoCrTi0.5)Cx coating. (FeNiCoCrTi0.5)Cx coatings, without pores and cracks, are well metallurgically bonded with substrate. The coatings consist of BCC solid solution, Cr23C6 and TiC. The addition of diamond in (FeNiCoCrTi0.5)Cx coating leads to the instability of BCC solid solution and facilitates the precipitation of carbides, which causes carbides to become coarse and aggregate into large blocks. The hardness of (FeNiCoCrTi0.5)Cx coatings is much higher than that of the 45 steel, the average hardness of C12 coating is 4 times the hardness of substrate. Besides, the hardness of (FeNiCoCrTi0.5)Cx coating increases with the increase of diamond content. Nonetheless, compared to C6 coating, the C12 coating shows inferior tribological performance due to the brittleness. It is noteworthy that C6 coating with outstanding wear resistance has the potential to apply in various fields of machinery industry, marine engineering and aerospace.