Effect of Mo-V co-addition on the elastic properties and wear resistance of AlCoCrFeNi high-entropy alloy laser cladding coatings

AlCoCrFeNiMo_xV_1-x (x = 0, 0.25, 0.5, 0.75, and 1.0) high-entropy alloy coatings were fabricated on Q235 steel via laser cladding. The microstructure, elastic properties, and wear resistance at room temperature and intermediate-to-high temperatures were systematically investigated. The coatings are composed of BCC, σ, and B2 phases, with grain morphology transitioning from dendritic to columnar structures. First-principles calculations and nanoindentation tests reveal that co-addition of Mo and V significantly enhances the deformation resistance and wear performance of the BCC phase. Microhardness and wear resistance initially increase with increasing x, peaking at x = 0.5 before declining. This can be attributed to the formation of a high-elastic modulus BCC phase and the dispersion strengthening of the σ phase. Across the temperature range from room temperature to 800 °C, the wear resistance of each coating initially improves, reaching an optimal at 600 °C before the deterioration. This behavior is driven by the combined effect of oxidation kinetics and friction pressure, which promotes the in-situ formation of a continuous and dense oxide film. However, the volatilization of V₂O₅ and MoO₃ at 800 °C leads to a deterioration in wear resistance.