Hot workability of γ + α2 titanium aluminide: Development of processing map and constitutive equations

Gamma titanium alumindes are intermetallics, which have very narrow working range. Hot isothermal working is the most suitable process for hot working of alloy. Accordingly, hot isothermal compression test is carried out on reaction synthesized and homogenized titanium aluminide alloys at different temperatures and strain rates using Gleeble thermomechanical simulator. Three alloys of Ti48Al2Cr2Nb0.1B (atom%) have been used in the study. Stress–strain data obtained from the test has been used to construct processing map, which indicates the safe and unsafe working zone. Strain rate sensitivity and Zener–Hollomon parameter has been calculated. Further, constitutive equations have been generated and verified. It is found that alloy has good workability in the temperature range of 1223–1423 K at strain rates of 0.01–0.001 s−1. In this range of parameters, the alloys nearly follow the constitutive equations.

► Deformation studies of five TiAl alloys carried out through processing map.
► DRX domain and superplastic domain identified in power efficiency map.
► Safe working zone for alloys found at 1223–1423 K at strain rates (10−2–10−3 s−1).
► Strain rate sensitivity, activation energy, Zener Hollomon parameter (Z) are obtained.
► Constitutive equations derived and verified. DRX grain size correlated with Z.