Microstructural evolution and mechanical properties of Ti–5Al–3Mo–3Cr–1Zr-0.15Si alloy by annealing treatments

Titanium alloys, especially α+β type ones, are usually subjected to diverse heat treatments for tailoring their microstructures and mechanical properties. In this study, we investigated the microstructure, microtexture, and mechanical properties of a novel α+β type Ti–5Al–3Mo–3Cr–1Zr-0.15Si alloy with annealing treatments including single annealing, duplex annealing, and β annealing. It was found that the sizes of β grains, α colonies and secondary α, as well as the volume fraction of primary α, are closely dependent on the annealing temperatures. Additionally, the crystallographic orientations of the α and β phases change with specific annealing treatments while consistently adhering to the Burgers orientation relationship. Despite the variations in microtexture intensity with different treatments, the initial microtexture components are retained due to the texture memory effect. The microstructure and mechanical property characterizations revealed that the secondary α phase exert more contribution to the strengthening effect than the primary α phase, while continuous and straight grain boundary α phase undermines the ductility. Duplex annealing, which produces fine β grains and fine secondary α phase, achieves a good balance between the strength and ductility of the alloy.