The deformation behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength β titanium alloy is systematically investigated by isothermal compression in α + β field with the deformation temperatures ranging from 1003 K to 1078 K, the strain rates ranging from 0.001 s⁻¹ to 1 s⁻¹ and the height reduction is around 50%. Essentially, the flow stress-strain curve of isothermal compression in α + β field exhibits a flow softening feature when the strain rate is higher than 0.1 s⁻¹ as while it exhibits a steady-state feature as the strain rate is lower than 0.1 s⁻¹. The peak stress increases with a decrease in deformation temperature and the increase of strain rate. The activation energy for deformation in α + β field was calculated and the average activation energy of 271.1 kJ/mol. The microstructure observation reveals that the isothermal deformation in the α + β field of the alloy is mainly controlled by the dynamic recovery mechanism accompanied with the secondary dynamic recrystallizitation of β phase. The α phase shows an obvious pinning effect for the movement of dislocations. During deformation, the α phase was elongated and fragmented.

The investment casting of TiAl alloys has become the most promising cost-effective technique for manufacturing TiAl components. This study aimed to investigate a series of problems associated with the investment casting of TiAl alloys. The mold filling and solidification of this casting model were numerically simulated using ProCAST. Shrinkage porosity was quantitatively predicted by a built-in feeding criterion. The results obtained from the numerical simulations were compared with experiments, which were carried out on Vacuum Skull Furnace using an investment block mold. The investment casting of TiAl grating was conducted for verifying the correctness and feasibility of the proposed method. The tensile test results indicated that, at room temperature, the tensile strength and elongation were approximately 675 MPa and 1.7%, respectively. The microstructure and mechanical property of the investment cast TiAl alloy were discussed.

In this study, an easily controlled transformation similar to the β + α → β + α + γ and the analysis of metastable phases in a β solidifying Ti-44.5Al-8Nb-2.5V alloy were investigated. Therefore, a liquid alloy copper-quenching followed by annealing at an application temperature (850 °C) has been carried out. Following quenching, a microstructure composed of several supersaturated phases—the basket-weave β₀ (β_bv) phase, the plate-like α₂ (α_p) phase and the stripe-like γ (γ_s) phase—was obtained. In the annealing processes, phase transformations in the prior β_bv and α_p phases domain corresponded nicely to the β + α → β + α + γ transformation during solidification. Also, in the annealed γ_s phase, the kinetics of the phase transformations involving the metastable L1₂ phase was firstly detected by transmission electron microscopy (TEM). The L1₂ phase had a lattice structure similar to the γ phase, whereas the composition of the phase was similar to the α₂ phase. The formation of the γ pre-twin phase with an anti-phase boundary (APB) was detected in the γ_s phase of the matrix. The orientation relationships between the γ_s and precipitated: γ (γ_p) phase are <101]γ_s//<114]γ_p, (10 $\overline{1}$ )γ_s//( $\overline{1}$ 10)γ_p and (0 $\overline{1}$ 0)γ_s//(22 $\overline{1}$ )γ_p.