Microstructures, Hardness and Corrosion Behaviors of FeCoNiNb(0.5)Mo(0.5) and FeCoNiNb High-Entropy Alloys

This study investigates the effects of niobium and molybdenum on FeCoNi alloy, including on the microstructures and hardness of FeCoNiNb(0.5)Mo(0.5) and FeCoNiNb alloys, and the polarization behaviors of these alloys in 1 M sulfuric acid and 1 M sodium chloride solutions. The results in this study indicate that both FeCoNiNb(0.5)Mo(0.5) and FeCoNiNb alloys had a dual-phased dendritic microstructure; all of the phases in these alloys were solid solution phases, and no ordering was observed. Therefore, the solid solution effect significantly increased the hardness of these two alloys; in particular, FeCoNiNb alloy had the highest hardness of the alloys of interest. The corrosion resistance of FeCoNiNb(0.5)Mo(0.5) and FeCoNiNb alloys was less than that of FeCoNi alloy because of their dual-phased dendritic microstructures. The corrosion resistance of the FeCoNiNb(0.5)Mo(0.5) alloy exceeded that of the FeCoNiNb alloy in these solutions. However, FeCoNiNb(0.5)Mo(0.5) and FeCoNiNb alloys exhibited a favorable combination of corrosion resistance and hardness.