Evaluation of the Influence of Tantalum on the Microstructural, Mechanical and Electrochemical Properties of Ti-Mo-Zr-xTa Alloys for Use in Biomedical Devices.

New titanium alloys for biomedical applications are being developed to avoid the use of aluminum and vanadium, which may raise concerns regarding their long-term biological effects. In this study, the effect of tantalum content on the microstructure, hardness and electrochemical behavior of Ti-Mo-Zr-xTa alloys (x = 5, 10 and 15 wt.%) obtained by vacuum arc melting (VAR) was investigated. Characterization included assessment of samples via optical microscopy, scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) analysis and X-ray diffraction (XRD). Mechanical response and corrosion resistance were assessed using Vickers microhardness and electrochemical tests in Ringer's solution, respectively. The X-ray diffraction results indicated that the β phase was predominant in all three compositions. Furthermore, the increased tantalum content promotes the stability of this phase and reduces the α″ martensite contribution observed in alloys with lower tantalum content. The mean microhardness decreased as the tantalum content increased, although measurements showed less dispersion with increasing indentation load. All alloys exhibited passive behavior in Ringer's solution, with the Ti-15Mo-7Zr-15Ta alloy showing the lowest corrosion current density and corrosion rate.