Evolution of microstructure in niobium rich (α<inf>2</inf>+γ) based titanium aluminide alloy during hot compression

A β-solidified nearly lamellar γ-TiAl (α2+γ) based alloy was investigated to understand the evolution of microstructure during hot isothermal compression test at 1050 °C (below eutectoid). Cylindrical samples were compressed to different true strains up to 60%. The deformed samples were then characterized using scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) to understand the active deformation mechanisms. Dynamic flow softening behavior, i.e., dynamic recrystallization (DRX) type flow was observed. While no new strain induced phases were observed, there were minor changes in the phase fractions as a function of strain. Kinking and bending of lamellae at certain areas in the microstructure of compressed samples were predominant. Preliminary analysis by TEM indicated the presence of twinning in both γ and β phases.