Effect of Al content on the oxidation behavior of NiCoCrAlYHf alloys at 1100 ℃

The effect of Al content on the oxidation behavior of NiCoCrAlYHf alloys (Ni44Al16, Ni42Al18 and Ni40Al20) at 1100 ℃ is investigated in this study. It is demonstrated that the oxidation rate of NiCoCrAlYHf alloy decreases with the increase of Al content. The Al content play the important role on the oxidation rate by determining the columnar grain size of α-Al2O3 scale and the distribution of Y/Hf-rich oxides within the α-Al2O3 scale, which shows large influence on O diffusion rate. Those findings can provide guidance for the high-performance NiCoCrAlYHf coatings design.