TiAl alloys with similar compositions but different constituents have been designed. Both β/B2-rich and β/B2-lean alloys shows impressive superplasticity at 1000 °C. The β/B2-rich alloy shows much larger cavity sizes than β/B2-lean alloy. Cavities in β/B2-rich alloy are more likely to elongate along the tensile axis. The cavity growth rate of γ-TiAl is much higher than that of ordinary alloys.