Microstructural understanding of high-temperature oxidation behaviour of selective laser melted Inconel 718 superalloy in CO2 atmosphere

In this work, the oxidation behavior of Inconel 718 superalloy fabricated by selective laser melting was investigated in the CO2 atmosphere at 1000 and 1100 °C. Results show that the structure of the oxide scales is strongly dependent on the grain position (grain boundary and grain interior) and the oxidation temperature. It forms six-layer and four-layer oxide scales at the grain boundary region after 300 min oxidation at 1000 and 1100 °C, respectively, producing three-layer oxide scales in the intragranular area. The formation mechanisms of the oxide scale were discussed. Additionally, the Kirkendall voids and internal oxidation in the matrix preferentially form at 1100 °C.