Aging response of the Ti–35Nb–7Zr–5Ta and Ti–35Nb–7Ta alloys

Titanium alloys are the best metallic biomaterials to be used for implant fabrication. However, the Ti–6Al–4V alloy must be replaced because of V and Al toxicity and, non-toxic β-stabilizer elements should be used. This work reports the results found after aging treatments of the alloys Ti–35Nb–7Zr–5Ta and Ti–35Nb–7Ta. The alloys were arc melted, homogenized, hot rolled, solubilized and finally aged at several temperatures, from 200 to 700 °C for 4 h. Afterwards, the alloys were aged at 300 and 400 °C for 90 h. Characterization was mainly performed by X-ray diffraction, which did not indicate the precipitated phases during the 4 h aging, while it showed that during the 90 h aging the precipitated phases were α and ω. The 4 h aging showed that the highest hardness values were found when the alloys were aged at 400 °C. The values found were HV (336 ± 9) for the alloy Ti–35Nb–7Zr–5Ta and HV (317 ± 13) for the alloy Ti–35Nb–7Ta. It was observed that Zr suppresses ω precipitation but also hinders hardness improvement.