The Electrochemical and Mechanical Behavior of Bulk and Porous Superelastic TiZr-Based Alloys for Biomedical Applications

Titanium alloys are well recognized as appropriate materials for biomedical implants. These devices are designed to operate in quite aggressive human body media, so it is important to study the corrosion and electrochemical behavior of the novel materials alongside the underlying chemical and structural features. In the present study, the prospective TiZr-based superelastic alloys (Ti-18Zr-14Nb, Ti-18Zr-15Nb, Ti-18Zr-13Nb-1Ta, atom %) were analyzed in terms of their phase composition, functional mechanical properties, the composition and structure of surface oxide films, and the corresponding corrosion and electrochemical behavior in Hanks' simulated biological solution. The electrochemical parameters of the Ti-18Zr-14Nb material in bulk and foam states were also compared. The results show a significant difference in the functional performance of the studied materials, with different composition and structure states. In particular, the positive effect of the thermomechanical treatment regime, leading to the formation of a favorable microstructure on the corrosion resistance, has been revealed. In general, the Ti-18Zr-15Nb alloy exhibits the optimum combination of functional characteristics in Hanks' solution, while the Ti-18Zr-13Nb-1Ta alloy shows the highest resistance to the corrosion environment. The Ti-18Zr-14Nb-based foam material exhibits slightly lower passivation kinetics as compared to its bulk equivalent.