The microstructure, mechanical properties, and oxidation behavior of beta-gamma TiAl alloy with excellent hot workability

摘要

New type beta-gamma TiAl alloy of nominal composition of Ti-44Al-4Nb-4V-0.3Mo-Y (at%) was fabricated by induction skull melting, which was designed based on the study of the microstructural effects of Mo, Cr, V, and Nb on TiAl alloy. The microstructure, oxidation resistance, hot workability, and tensile properties were studied by SEM in BSE mode, XRD, Gleeble 3800, as well as Instron 5500 R, respectively. The oxidation resistance of this new designed Mo containing beta-gamma TiAl alloy was better than that of only Nb and V containing beta-gamma TiAl alloy. With a better hot workability at temperature under 1200 ℃, Ti-44Al-4Nb-4V-0.3Mo-Y alloy was successfully hot forged at 1150 ℃ with a traditional hydraulic machine without thermal insulation measure. Though containing abound order β_0 phase, the new fabricated beta-gamma TiAl alloy still has a high elongation at 850 ℃, because of less α_2 + γ lamellar colonies containing. Benefits of partly replacing Mo with V was avoiding omega phase precipitation, and not damaging the hot workability.