Oxidation resistance of TiAl alloy improved by hot-pack rolling and cyclic heat treatment

The isothermal oxidation behavior of two TiAl alloys (as-HIP and as-RHT) were compared to explain the effect of microstructure on the oxidation resistance of TiAl alloy. After hot-pack rolling and cyclic heat treatment, the size of lamellar colonies was refined from 35.4 μm to 21.5 μm, and the β/B2 phase was effectively removed. It is concluded that the as-RHT TiAl alloy has better oxidation resistance than the as-HIP TiAl alloy. The main reason is due to refinement of lamellar colony size, elimination of β/B2 phase, uniform distribution of Nb and Mo, and the crushing of Y compounds. •Rolling and cyclic heat treatment can refine lamellae and eliminate β/B2 phase in TiAl alloy.•The elimination of β/B2 phase helps forming dense Al2O3, Nb- and Mo-rich layers.•The negative effects of Y on the oxidation resistance of TiAl alloy is discussed.•Refining lamellae, eliminating β/B2 phase, uniform distribution of Nb and Mo and breaking yttrium compounds are good for oxidation resistance of TiAl alloy.