Deformation behavior of differently processed γ-titanium aluminides

A short review on forging and rolling of TiAl-ingot material as well as HIPed prealloyed powder is presented. The ingots show a lamellar microstructure with a strong cast texture and alignment of the lamellae, resulting in strong mechanical anisotropies. Hot-forging and heat-treatments are required to obtain isotropic mechanical properties due to a more random texture. The influence of strain rate and temperature on the development of microstructure during forging was studied. The role of twinning and dynamic recrystallization (DRX) will be discussed. After rolling a fine-grained microstructure is observed with a strong modified cube texture, which give rise to improved strength and creep resistance in the transverse direction (TD) of the sheets. Above 1000 °C the sheets can be deformed superplastically. DRX gives microstructures which obey a Zener–Hollomon power law.