Effect of aging treatment on the microstructure and properties of cold rolled Ti-10V-2Fe-3Al alloy

As a typical metastable titanium alloy with high strength and toughness, Ti-10V-2Fe-3Al titanium alloy has found wide applications in aerospace industry to replace forging steel components for light weight, long service life and high reliability. In the present study the microstructure evolution and mechanical properties of cold rolled Ti-10V-2Fe-3Al alloy undergoing aging treatment were characterized by optical microscopy, X-ray diffraction, transmission electron microscopy and mechanical testing, in attempt to understand the relationship between the microstructural evolution and aging treatment temperature and time. It is revealed that the secondary α phase had a very short propagation time to nucleate, and holding 5 min could give rise to the transformation from β phase to secondary α phase when cold rolled alloy suffered from aging at 550°C. This could be attributed to the large amounts of dislocations and grain boundaries by cold deformation, which provide nucleation sites for α phase. Increasing aging time could accelerate the transformation from β phase to secondary α phase. With aging at 550°C for 30 min, a large amount of fine secondary α phase formed, offering a good combination of strength and ductility. With increasing aging time the coarsening secondary α phase led to a decrement of strength of the alloy.