Deformation behavior of dual-phase LTSP Ti₃Al based alloy

Ti₃Al based alloys have been widely reported for their admirable superplasticity in the temperature range of 900-1000°C. However, the superplastic behavior of temperature lower than 900°C was seldom reported. Dual phase (α₂+β) Ti₃Al-10Nb alloy has shown superior superplastic elongation of 1500% at 960°C and 2×10^-4 s ^-1. In this paper, it aims to investigate the superplastic behavior at lower temperature (700-900°C). The relationship of texture characteristics, phase transformation phenomena, and deformation mechanism at lower temperature (below 900°C) are studied. The optimum low-temperature superplastic condition with an elongation of 333% was occurred at 850°C and 5×10^-4 s^-1. With abundant hexagonal α₂' laths formed inside the β grains, the major accommodation process via dislocation slip across the β grains is impeded. It leads to premature failure and lower tensile elongations at lower temperature. Moreover, with the minor operating of grain rotations and grain boundary sliding, the texture intensity decreases significantly at temperature 850°C.