Deformation behavior and microstructural evolution of directionally solidified TiAlNb-based alloy during thermo-compression at 1373–1573 K

Highlights: • Deformation resistance is excellent for directionally solidified TiAl alloy. • Ordering temperature of B2 phase is in the range of 1373–1573 K. • Shear deformation feature is exhibited as axial compression at 1373–1573 K. - Abstract: Alloy Ti44Al6Nb1.0Cr2.0V0.15Y0.1B is newly designed and melted by vacuum consumable melting method, and is then prepared by cold crucible directional solidification (CCDS) technology. Thermo-compression experiment is carried out on CCDS billets at 1373–1573 K. Experimental results show that, when compressing direction (CD) is perpendicular to columnar grains, higher deformation active energy of Q = 689.8 kJ/mol can be acquired which means excellent creep resistance in radial direction; the microstructural evolution with different lnZ parameters is investigated by electron back scattering diffraction and the deformation mechanism is discussed; the ordering temperature of B2/β phase is deduced to be in the range of 1200–1250 °C. When the CD is parallel to the columnar grains, a much higher peak stress is acquired which means more excellent creep resistance in the axial direction; the shearing deformation feature is presented and the schematic of deformation mechanism is given.