Thermodynamic, kinetic and mechanical modeling to evaluate CO2-induced corrosion via oxidation and carburization in Fe, Ni alloys

A computational framework integrating thermodynamics, kinetics, and mechanical stress calculations is developed to study supercritical CO2 induced corrosion in model Fe-based MA956 and Ni-based H214 alloys. Empirical models parametrized using experimental data show surface oxidation and sub-surface carburization for a wide range of thermodynamic conditions (800-1200 °C, 1-250 bar). CALPHAD simulations based on empirical models demonstrate higher carburization resistance in H214 compared to MA956 below 900 °C and through-thickness carburization in both alloys at higher temperatures. Finite element modeling reveals enhanced volumetric misfit induced stresses at oxide and carbide interfaces, and its critical dependence on the carbide chemistry and concentration.