Phase transformation behavior of alumina grown on FeAl alloys with reactive element dopants at 1273Â K

The short-term isothermal oxidation behavior of B2 FeAl alloys doped with different reactive elements (REs) at 1273 K was investigated. All the RE-doped alloys showed retarded phase transformation from θ-to α-Al2O3 as compared to the RE-free alloy. The Y- and La-doping even led to much lower transformation rate than the Hf-, Zr- and Ce-doping. The effect mechanism associated with RE ion size and valence on the phase transformation of alumina was discussed. The additions of RE ions which have large size and matched valence with Al ions could be anticipated to inhibit the transformation more effectively and the combined effects of retarding θ-α phase transformation, promoting α phase nucleation and suppressing Al outward diffusion produced by RE doping might provide FeAl with improved oxidation property.