Hot deformation behavior of β-solidifying TiAl based alloy

Abstract

High-temperature mechanical behavior and microstructure evolution during hot deformation of an as-cast β-solidified Ti–44Al–2V–1Nb–1Zr–0.2Gd–0.2B alloy were studied. The as-cast alloy was subjected to uniaxial compression at temperatures from 1100 to 1250 ◦C and strain rates in the range 0.001–1 s−1. Different mechanisms of microstructure evolution were found to operate depending on deformation temperature and phase fields. Transformation of the initial lamellar microstructure into globular one in the α2 + γ and α + γ phase fields were associated with dynamic recrystallization/spheroidization processes. Dynamic recrystallization was the controlling process of the microstructure evolution in the α and α + β phase fields. Deformation in all phase fields resulted in microstructure refinement which, in turn, induced superplasticity under certain temperature-strain rate conditions. The relationships between mechanical behavior and microstructure after deformation were discussed.