Fine duplex Ti-48Al alloy with high strength produced by forging based on near-γ microstructure

TiAl-based alloy is an excellent high-temperature structural material, but poor hot workability has been the bottleneck hindering its development. In this study, we take into account the hot workability and mechanical properties of Ti-48Al alloy through microstructure adjustment. Powder metallurgy Ti-48Al alloy prepared by vacuum sintering is used as the raw material, which has a near-γ microstructure composed of equiaxed grains. Although the composition is simple, the alloy achieves high mechanical properties after forging with 75 % deformation. Controlling the forging temperature to 1300 °C can make the microstructure transform into a duplex structure composed of γ/α2 lamellar colonies and γ equiaxed grains. As-forged alloy has an ultimate tensile strength of 650 ± 17 MPa and a yield strength of 644 ± 16 MPa at room temperature. It still maintains high strength at high temperature, with ultimate tensile strength of 684 ± 19 MPa at 500 °C, 700 ± 19 MPa at 700 °C, and 320 ± 10 MPa at 900 °C. In addition, the alloy has good ductility with elongation of 58.2% due to dynamic recrystallization at 900 °C.