Oxidation behavior of Hf-modified aluminide coatings on Haynes-188 at 1050 °C

► Aluminide coatings with/without Pt, Hf on Haynes 188 were tested. ► Test was carried out at 1050 °C in air for up to 4670 h. ► Hf additions in (CoNi)Al coatings improved the oxide performance. ► HfO2 particles were formed and embedded in the Al2O3 scales. ► Pt-doping improved oxidation resistance of (CoNi)Al with/without Hf.