Research on oxidation behavior of Inconel 718 nickel-based superalloy by laser powder bed fusion

To investigate the high-temperature oxidation characteristics of Inconel 718 alloy fabricated by Laser Powder Bed Fusion (LPBF) and provide theoretical support for its application in the aerospace field, this study took LPBF Inconel 718 alloy with multi-stage post-treatment as the research object, conducted high-temperature oxidation experiments at 900℃ for 88 h, and systematically studied its oxidation behavior and mechanism by combining characterization methods such as oxidation kinetics analysis, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). The results show that the LPBF Inconel 718 alloy has an oxidation exponent n ≈ 2.7 and an oxidation rate constant k = 0.0012 , exhibiting enhanced high-temperature oxidation resistance. Its oxide film is continuous and dense, composed of Cr 2 O 3 , TiNbO 4 , FeNiO 4 , Cr 2 NiO, and Fe 2 O 3 , with no NiO phase formed. The oxidation process presents obvious layered characteristics: Cr 2 O 3 and a small amount of TiNbO 4 are formed in the initial stage, Fe 2 O 3 and spinel-type composite oxides are generated in the middle stage, and TiNbO 4 enriches at the film/substrate interface in the later stage. This stratification originates from the coupled effects of thermodynamic stability, elemental diffusion kinetics, and local oxygen potential. The barrier effect of the dense oxide film and the regulatory role of the unique microstructure of LPBF jointly contribute to the improved oxidation-retardation behavior.