A fundamental study of Fe–Cr binary alloy–oxide film interfaces at 288 °C by computational chemistry calculations

A quantum chemical molecular dynamics method was used in order to understand the oxide film degradation mechanism at metal/metal–oxide interfaces. The present study shows that oxygen diffusivity in the metal is significantly higher at a Fe–Cr/Fe2O3 interface compared to a Fe–Cr/Cr2O3 interface. This indicates that Cr2O3 enables protection of the surface for a longer period of time than Fe2O3 in a high temperature environment. Applied tensile strain enhances the oxygen mobility towards the metal surface. This process helps to increase the oxidation of the metal surface by forming metal oxygen bonds. Atomic charge analysis reveals that the oxygen atoms are negatively charged and the chromium atoms are more highly positively charged than iron ones. The negatively charged oxygen atoms are able to make covalent bonds with the positive metal atoms. This charge transfer process facilitates the formation of metal–oxygen bonds and weakens the metallic bonds.