High-Performance Ti-6554 Alloy Manufactured Using Irregular Powder via Vacuum Pressureless Sintering Followed by Forging

Ti-6554 (Ti-6Cr-5Mo-5V-4Al) alloy has attractive potential as a new structural material in the aviation field due to its excellent mechanical properties. However, it is expensive to manufacture, which can limit its application. Powder metallurgy (PM) is an economic technology to reduce the cost of titanium alloys. In this study, PM Ti-6554 alloy was prepared using irregular powder via vacuum sintering followed by forging. The influence of cooling rate (air cooling and water quenching) of as-forged sample on its microstructure was studied by scanning electron microscopy, electron backscatter diffraction and other analytical means. Experimental results showed that different cooling rates determined the structures of alpha and beta phases. Compared with air-cooled sample, the water-quenched sample only had beta phase microstructure without alpha phase precipitates. As-forged PM Ti-6554 alloy subjected to water quenching achieved ultimate tensile strength of 942 MPa and elongation of 20% and also had fine beta grains of 10 mu m. After solution treatment and aging, the sample exhibited high ultimate tensile strength (1211 MPa) and elongation (13.8%). Overall, PM Ti-6554 alloy possessed a good combination of high strength and reasonable ductility. This work marks a vital step forward in the application of high-performance PM Ti-6554 alloys.