Preparation of Diamond Reinforced NiCoCrTi0.5Nb0.5 High-Entropy Alloy Coating by Laser Cladding: Microstructure and Wear Behavior

The diamond enhanced (NiCoCrTi0.5Nb0.5)Cx (x = 3, 6, 12 wt.%) high-entropy alloy coatings were well-prepared by laser cladding, which are denoted as C3, C6 and C12, respectively. The macroscopic morphology, phase, microstructure, hardness and wear resistance were investigated. The coatings without pores and cracks, are well-metallurgically bonded with the substrate. The width, melting depth and dilution rate of (NiCoCrTi0.5Nb0.5)Cx coating decrease with the increase of diamond content. The coatings are mainly composed of BCC solid solution, (Ti,Nb)C and Cr3C2. The increase of diamond content results in the precipitation of (Ti,Nb)C and Cr3C2, and the coating with x = 12 wt.% retains more diamonds. The hardness of coatings is much higher than that of the substrate. As the diamond content increases, the average hardness of (NiCoCrTi0.5Nb0.5)Cx coating increases first and then decreases. The abrasive wear occurs in each coating. The wear depth, roughness and wear rate decrease first and then increase as the diamond content increases. The C6 coating with the better wear resistance produces a smooth worn surface, which indicates that C6 coating can be fully applied to various tools, molds and mechanical parts.