Evolution of microstructure and high-temperature oxidation behavior of inconel 625 alloy additive manufactured reinforced with CrN particles

To systematically elucidate the synergistic mechanisms of CrN particles on microstructure regulation and high-temperature oxidation behavior of Inconel 625 (IN625) deposits, IN625 and IN625/CrN composite deposits were fabricated using directed energy deposition-arc (DED-Arc), and the effects of CrN particles on microstructure evolution and high-temperature oxidation behavior were systematically investigated. The results indicate that the introduction of CrN promotes the precipitation of nitrides/carbonitrides, which act as heterogeneous nucleation sites to significantly refine the γ-Ni matrix grains and transform the Laves phase from a continuous interdendritic network into a discrete distribution. During oxidation at 1100 ℃, the IN625/CrN composite exhibited superior oxidation resistance, with the mass gain reduced by 92.1% and the oxidation rate constant decreased by 64.8% compared with IN625. Mechanism analysis reveals that CrN facilitates Cr diffusion through grain refinement, leading to the formation of a dense Cr₂O₃ protective layer, while simultaneously suppressing the outward diffusion of Ni and Fe and reducing the formation of non-protective oxides. As a result, the adhesion of the oxide scale is improved and spallation is effectively inhibited. These findings demonstrate that the incorporation of CrN particles can significantly enhance the microstructure and high-temperature oxidation resistance of IN625 deposits.