First approach for thermodynamic modelling of the high temperature oxidation behaviour of ternary γ'-strengthened Co-Al-W superalloys

In the present work, thermodynamic modelling of the high temperature oxidation behaviour of a γ'-strengthened Co-base superalloy is presented. The ternary Co-9Al-9W alloy (values in at%) was isothermally oxidised for 500h at 800 and 900°C in air. Results reveal that the calculated oxide layer sequence (Thermo-Calc, TCNI6) is in good agreement with the formed oxide scales on the alloy surface. Furthermore, prediction of the influence of oxygen partial pressure on Al2O3 formation is presented. The modelling results indicate pathways for alloy development or possible pre-oxidation surface treatments for improved oxidation resistance of the material.