Formation Mechanism of Oxide Film on the Surface of Inconel 718 Alloy Prepared by Conventional Process and Selective Laser Melting at 650 ℃

Inconel 718 alloy was prepared based on selective laser melting (SLM) technology. Scanning electron microscopy and energy dispersive spectroscopy were used to analyze micro morphology and composition of oxides on the surface of Inconel 718 alloys prepared by conventional process and SLM technology, respectively, after oxidation at 650 ℃ for different periods of time. The results showed that both flake and bulk oxides appearred on the surface of the two Inconel 718 alloys, and the growth rules of oxides were roughly the same. The oxidation resistance of Inconel 718 alloy prepared by SLM technology slightly better than that of Inconel 718 alloy prepared by conventional process. The flake oxides on the surface of the two Inconel 718 alloys were mainly formed by of oxygen elements into the matrix and being oxidized, and the bulk oxides were mainly formed by the outward diffusion of alloy elements and being oxidized. The main component of oxide film on the surface of two Inconel 718 alloys was iron oxide. With the prolongation of oxidation time, the oxide type gradually tended to Me₂O₃ oxide.