The Hot Deformation Behavior of Ti–48Al–2Cr–2Nb Intermetallic with Lamellar Initial Microstructure

The aim of this study is to investigate the hot deformation behavior of Ti–48Al–2Cr–2Nb intermetallic with lamellar initial microstructure. Hot compression tests were performed at temperatures of 1000, 1050, 1100, and 1150°C, and strain rates of 0.001, 0.01, and 0.1 s^–1. The average strain rate sensitivity coefficient for the hot deformation of this intermetallic was calculated to be 0.17. The highest strain rate sensitivity coefficient, 0.29, was observed at 1100°C and a strain rate of 0.001 s^–1, while the lowest value, less than 0.12, was obtained at a strain rate of 0.1 s^–1 and temperatures between 1000 and 1100°C. The activation energy was 238 kJ/mol. At deformation temperatures of 1050°C, the dominant softening mechanism was bending of lamellae. The fraction of recrystallization is minimal at all strain rates. With increasing deformation temperature to 1100°C, recrystallization decreased and phase decomposition occurred. At 1150°C, deformation occurred through the formation of shear bands. Based on the energy consumption efficiency criteria, the deformation temperature of 1100°C and strain rate of 0.001 s^–1 were suggested as the optimal conditions for hot deformation of the Ti–48Al–2Cr–2Nb intermetallic with lamellar initial microstructure, with an efficiency of 44.8%.