Microstructure evolution and mechanical property of powder metallurgy Ti6Al4V alloy with high oxygen concentrations

Abstract

High oxygen Ti6Al4V alloys are fabricated by vacuum sintering and hot rolling using hydrogenation-dehydrogenation Ti6Al4V powder and ZrO 2 powder as raw materials. The complete dissolution of oxygen and zirconium atoms results in an increase in lattice constant and strength. As-rolled Ti64-ZrO 2 sample exhibits a bimodal structure with a fine acicular α phase of around 1 μm. Ti64-0.75 ZrO 2 alloy with equivalent oxygen content close to 0.6 wt.-% presents a good combination of the high tensile strength (1180.2 MPa) and sufficient elongation (7.3%). Therefore, the critical oxygen content for the ductile-to-brittle transition of powder metallurgy Ti6Al4V alloy can be improved by suitable preparation methods. The formation of a fine β transformation structure may be one of the reasons for maintaining sufficient ductility.