HIP temperature and properties of a gas-atomized γ-titanium aluminide alloy

The effect of HIP-temperature on the tensile properties of a powder metallurgical γ-titanium aluminide based alloy has been investigated in this study. Prealloyed, gas-atomized Ti–46Al–2Cr–2Nb powder was HIPʹed at temperatures between 1200 and 1300 °C. The observed as-HIP microstructures reflect the path of the HIP-process in the α+γ, α2+γ and α+β+γ phase fields. Yield stresses in the as-HIP conditions range from 460 to 715 MPa. They are accompanied by ductilities of 0.2 –1.7%. After heat treating to achieve fine duplex microstructures, yield stress levels from 515 to 585 MPa and ductilities from 0.4 to 1.6% are observed. Ductility improvements seem to be related to increasing amounts of lamellar grains and β-phase with concomitant lower strain hardening rates. The effect of HIP-temperature on tensile properties is small when microstructural differences are largely eliminated.