Improved Compressive Properties of TiAl Alloy with Ultrafine/Fine Grains Prepared by High-Energy Ball Milling and Hot-Pressing Sintering

In this paper, Ti-48Al-2Cr-2Nb alloy with ultrafine/fine-scale bimodal grain structure was prepared by high-energy ball milling and hot-pressing sintering. The microstructure, room temperature mechanical properties and fracture mechanism of the alloy were investigated by means of XRD, SEM, TEM, and compressive tests. The results show that the TiAl alloy with ultrafine/fine grained bimodal structure is mainly composed of equiaxed γ -TiAl grains, dispersed island-like α 2 -Ti 3 Al phase and a small amount of lamellar γ / α 2 microstructure, and possesses satisfied room temperature compressive properties, with the yield strength, fracture strength, and compression rate of 2047, 2693 MPa, and 4.85%, respectively. The fracture morphology is smooth, and the tear layer is small and thin, showing the fracture forms of translamellar and intergranular/interlamellar fractures.