Comparative studies on the oxidation and spallation behaviors of Y or Hf doped TiAlCr alloys at 1000 °C and 1100 °C

The oxidation behaviors of the TiAlCr alloys with and without reactive elements (REs) of Y or Hf were investigated under isothermal oxidation conditions at 1000 °C and 1100 °C, respectively. It was shown that the oxidation resistance of TiAlCr-0.4Hf was the best, followed by TiAlCr-0.4Y and the free-doped one at 1000 °C. After oxidation at 1100 °C for 200 h, the spallation ratio of the oxide layer on TiAlCr-0.4Hf was only about 2 %, nearly one-sixth and one-fourteenth of those for free-doped TiAlCr and TiAlCr-0.4Y, respectively. These results indicated that the addition of Hf could improve the interfacial toughness of the oxide layer, which benefited from the weak S segregation and the reductions of both imperfections (e.g., RE-rich oxides) and micropores at the oxide layer/alloy interface. These effects are achieved more efficiently than the Y addition, thereby ensuring a superior spallation resistance of the oxide layer on TiAlCr-0.4Hf alloy during high-temperature exposure.