Oxygen-induced refinement of α precipitates in an aged metastable β Ti-15-333 alloy

Increasing the strength of aged metastable β titanium alloys through refinement of intragranular α precipitates has been previously demonstrated using heterogeneous nucleation on structural and compositional non-uniformities. Here, we show that elevated oxygen levels (up to 1.7 at. %) can also induce α phase refinement during ageing of a β Ti-15-333 alloy, providing an additional pathway to obtain fine α laths. Moreover, oxygen-induced refinement combined with ω-assisted α nucleation resulted in significantly reduced α sizes of ∼50 nm. The finer α precipitates obtained with higher oxygen concentrations resulted in increased compressive yield strengths during micropillar compression compared to specimens without oxygen. These findings highlight the use of high oxygen contents to improve α microstructural refinement and precipitation strengthening in β Ti alloys.