Grain boundary energy affected initial oxidation on Ni-based superalloy revealed by in situ environmental TEM

Abstract Inconel 718 Ni-based polycrystalline superalloys exhibit excellent mechanical properties, while the type and nature of the grain boundaries are important for their corrosive properties. The effect of grain boundaries on initial oxidation is decisive for degradation, and the conventional method has difficulty revealing nanoscale grain boundaries with different angles. Atomic-scale initial oxidation on different boundaries in Inconel 718 alloys was systematically investigated by in situ environmental transmission electron microscopy (ETEM) with high spatial and temporal resolution. This study reveals the mechanism of intergranular oxidation in polycrystalline alloys and provides a new idea for improving the oxidation resistance of polycrystalline materials.