Processing Map and Hot Working Mechanism of As‐Cast Ti–42Al–5Mn Alloy

The research is focused on the hot deformation behavior of Ti–42Al–5Mn (at%) ingot produced by vacuum induction melting (VIM) and vacuum arc remelting (VAR). Firstly, the isothermal compression test is performed at the temperatures between 1100 and 1300 °C with the strain rates in the range of 0.001–10 s⁻¹. The processing map is plotted on the base of the strain–stress curves, and the constitutive equation is also established by regression analysis based on the experimental results. Secondly, different deformation features in β, γ phase, and γ lath of lamellae are investigated by electron probe micro analyzer (EPMA) and transmission electron microscope (TEM). The results reveal that, the alloy can be hot worked from 1300 °C–10 s⁻¹ to 1100 °C–0.1 s⁻¹, and the stress exponent and apparent activation energy are calculated to be 2.71 and 597 kJ mole⁻¹, respectively. It shows that, during the isothermal compression process, the γ phase usually has a higher dislocation density than β phase, and the γ lath of lamellae has generated both dislocation glide and deformation twinning.