Additively Manufactured Carbide and Nitride Doped Co22.2Cr22.2Ni22.2Cu22.2Nb11.2 High-Entropy Alloy for Surface Engineering Application

Metal-matrix composites have gained wide recognition owing to their superior tailorability, which surpasses that of traditional alloys. The development of multicomponent metal-based high-entropy alloy (HEA) systems has increased the potential for fabricating tunable composites for surface engineering applications. It has been established that the intrinsic properties of the composites are determined by the phases present in their base alloys, reinforcement types, and volumes. Herein, 5 wt.% of vanadium carbide, titanium nitride, and a combination of both ceramics were added to Co 22.2 Cr 22.2 Ni 22.2 Cu 22.2 Nb 11.2 HEA and fabricated via directed-energy deposition. The investigation highlights the first-time use of both ceramics and their synergistic utilisation as hybrid reinforcement in the directed-energy-deposited HEA. The candidate with the best hardness, tribological properties, and corrosion resistance was identified after various characterisations. It was found that the composite reinforced with a combination of both ceramics had the best microhardness value of 736 ± 30.79 HV. The titanium nitride-reinforced composite exhibited the highest wear resistance with 6.69 × 10⁻⁶ mm³/Nm at 20 N applied load. However, the synergy of both reinforcements offers enhanced lubricity, resulting in the lowest coefficient of friction of 0.071. A worn track analysis revealed that the samples were characterised by a transition from severe adhesive wear to cold-welded tribo-layer formation. The unreinforced HEA demonstrated the highest corrosion resistance with 567.79 Ω polarisation resistance and a corrosion rate of 0.6909 mm/year. It was concluded that the developed HEA and its composites are promising candidates for surface engineering application.