Utilising Ti3Sn intermetallic precipitates to achieve high strength Ti-Nb-Sn alloys

Metastable β Ti alloys based on Ti-Nb possess good biocompatibility and a low elastic modulus, which makes them candidate materials for implant devices within the biomedical industry. However, these alloys typically suffer from inferior mechanical strengths compared to commercial alternatives. One method shown effective at improving the strength of Ti-Nb alloys is the formation of precipitate species that pin and refine the grain size. However, currently little is known about the phase equilibria surrounding such compositions and the effect of this strengthening mechanism on the elastic properties of the alloy. As such, this study considers a series of Ti-Nb-Sn alloys to indicate the phase boundaries of the Ti 3 Sn intermetallic phase and considers the effect of this intermetallic precipitate on the mechanical response. The strengths of the precipitate forming samples were shown to be highly correlated with precipitate fraction, however, some suffered from incomplete recrystallisation and abnormal grain growth which significantly limited the absolute strengths that could be achieved. As such, potential routes forward for the development of these alloys have been discussed. • Ti-Nb-Sn alloys with 8% Sn refined grain size, even with low Ti 3 Sn volume fractions. • Ti 3 Sn precipitates hindered recovery, causing textured samples with sub-grain boundaries. • Higher solute content improved strength but raised modulus.