The role of Dy and Hf doping on oxidation behavior of two-phase (γ′ + β) Ni-Al alloys

To understand the role of reactive elements in affecting high-temperature oxidation behavior of two-phase (γ′ + β) Ni-Al alloys, Dy and Hf modified Ni-30Al alloys were designed. The results of oxidation tests conducted at 1100 °C indicated that Dy effectively reduced the oxide scale growth rate and enhanced the scale adhesion, but Hf had no significant effect, especially on scale adhesion, which is very different from that in single phase β-NiAl. Possible mechanisms were discussed by combining the solid solubility of Dy and Hf in NiAl and Ni3Al. A principle for selection of reactive element used for single doping was proposed.