Atomistic modeling of oxide-carbide growth on FeCr alloy surface in high-temperature CO2

This study investigates the atomistic mechanism of oxide-carbide growth on FeCr alloy surface. Simulation results demonstrate that Cr atoms segregate outward and form chain-like oxide above the surface initially. Afterward, more C atoms and O atoms penetrate into the alloy, leading to the growth of inner oxide and interior carbide. Meanwhile, driven by the oxidation-induced internal stress, Fe atoms in the inner oxide move outward and form Fe-rich outer oxide. Interestingly, the oxide-carbide growth is strongly affected by the temperature but not sensitive to the CO2 concentration at the initial stage. These results coincide with experimental and DFT study. •At the initial stage, Cr atoms in the alloy surface segregate outward and form chain-like oxide above the surface initially.•C atoms and O atoms penetrate into the alloy, leading to the growth of inner oxide and interior carbide.•Driven by the oxidation-induced internal stress, Fe atoms in the inner oxide move outward and form Fe-rich outer oxide.•The oxide-carbide growth is strongly affected by the temperature but not sensitive to the CO2 concentration at the initial stage.