Improving oxidation resistance of aluminide coatings by alloying elements from underlying superalloys

This study focused on the effect of superalloy composition on the oxidation resistance of aluminide coatings. Aluminide coatings were deposited on nickel-based superalloys, Inconel 718 and Mar-M247, with different compositions. The results indicated that the Inconel 718 coatings were enriched with Fe, while the Mar-M247 coatings were enriched with Co. After isothermal oxidation at 950°C, the Al₂O₃ scale of the Inconel 718 coatings was primarily α-Al₂O₃, while that of the Mar-M247 coatings was composed of θ-Al₂O₃ and γ-Al₂O₃. The Fe element in Inconel 718 coatings facilitated the transformation from metastable Al₂O₃ to stable α-Al₂O₃, leading to improved oxidation resistance.