Abstract
In this study, the surface of NiCoCrAlHf alloy was preoxidized with a high-temperature flame to improve its high-temperature oxidation resistance. A dense Al2O3 oxide scale was formed on the surface of NiCoCrAlHf after flame pre-oxidation, which has an important influence on the consumption of Al in the β-phase and the surface morphology after the oxidation experiment. The results show that the oxide-layer area of the original sample was 1.81-fold larger than that produced after the 48- and 300-h oxidation cycles, while the oxide-layer area of the flame-preoxidized sample was only 1.16-fold larger. In addition, the γ'-phase area of the original sample was 1.31-fold larger, while that of the flame-preoxidized sample was only 1.28-fold larger. The area changes of the oxide layer and the γ'-phase indicate that the high-temperature oxidation resistance of the NiCoCrAlHf alloy was further improved by Hf-doping modification.
Graphical abstract
