Impact of ruthenium on mechanical properties, biological response and thermal processing of β-type Ti–Nb–Ru alloys

In this paper, we present further work on the influence of minor additions of Ru to the Ti–20Nb alloy system, with a primary focus on mechanical properties of the as-cast material, along with microstructural response to elevated temperatures. Findings include high as-cast strengths and admissible strain values, up to 920 MPa and 1.5% respectively, along with moduli down to approximately 65 GPa in the as-cast state. Together with a significant increase in cell proliferation under MTS assay relative to controls, this indicates the chosen alloy system has significant promise for application in porous orthopaedic biomaterials, in particular those alloys with 0.5–1.0% Ru are deemed most suitable. Given their promise, preliminary investigation of the alloy system's response to thermal treatment was also undertaken. Statement of Significance The presented research, an investigation into the mechanical properties and response to thermal treatments of Ru-containing Ti–20Nb-base alloys, holds significance in the field of metallic biomaterials due to the heretofore limited investigation into the impact of Ru on the properties of biomedical, β-phase, Ti-based alloys. Given Ru's known beneficial impact on corrosion resistance, experimental confirmation of the impact of addition on mechanical properties was needed; that suitable mechanical properties, including yield strengths up to ∼930 MPa along with elastic admissible strains approaching 1.5%, were achieved is both promising in and of itself, and of significant note for further research into the field. Preliminary thermal and cell-proliferation studies are additionally provided to inform further studies.