ABSTRACT Among titanium alloys with non-toxic elements, the Ti-25Nb-25Ta alloy has good elastic behavior for applications in osseous implants, biocompatibility, and excellent corrosion resistance. The present study aimed to better the biocompatibility characteristics of Ti-25Nb-25Ta alloy modifying its surface through Plasma Electrolytic Oxidation (PEO) treatment. The formed oxide coating is amorphous and composed of two distinct porous formations: smaller hole-shaped pores and larger volcano-like pores. The regions with the formation of smaller pores and in the hole shaped presented the highest atomic percentage of the chemical element phosphorus. Nanoindentation tests have shown that the hardness of the Ti-25Nb-25Ta alloy is slightly lower than the commercially pure grade 2 titanium (a material used as reference), while elastic modulus measurements of Ti-25Nb-25Ta presented more suitable values for implant application (lower values when compared with titanium reference). After PEO treatment there were significant mechanical surface improvements (increased fairly surface hardness and decreased elastic modulus) for application in osseous tissue. Despite the Ti-25Nb-25Ta alloy presented excellent characteristics for applications in hard biological tissues, the PEO treatment better its features.

The present study produced binary titanium-niobium alloys Ti-xNb with high niobium percentage (x = 50, 80 e 90 wt.%) aiming to apply it as a base material in osseous implant devices. The produced TiNb alloys presented a cubic crystalline phase, lower corrosion rate than titanium, lower elastic modulus values, and superior cellular viability than titanium and niobium. The Ti50Nb alloy among all analyzed metallic substrates showed the best values of elastic modulus, corrosion properties, wettability, and cellular viability. Thus, this work suggests a Ti/Nb ratio close to 1 (Ti50Nb) displays optimum characteristics to apply in orthopedic devices.