Electrochemical corrosion and in vitro bioactivity of nano-grained biomedical Ti-20Nb-13Zr alloy in a simulated body fluid

The bioactivity and the corrosion protection for a novel nano-grained Ti-20Nb-13Zr at % alloy were examined in a simulated body fluid (SBF). The effect of the SPS's temperature on the corrosion performance was investigated. The phases and microstructural details of the developed alloy were analyzed by XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and TEM (Transmission Electron Microscope). The electrochemical study was investigated using linear potentiodynamic polarization and electrochemical impedance spectroscopy in a SBF, and the bioactivity was examined by immersing the developed alloy in a SBF for 3, 7, and 14 days. The morphology of the depositions after immersion was examined using SEM. Alloy surface analysis after immersion in the SBF was characterized by XPS (X-ray Photoelectron Spectroscopy). The results of the bioactivity test in SBF revealed the growth of a hydroxyapatite layer on the surface of the alloy. The analysis of XPS showed the formation of protective oxides of TiO₂, Ti₂O₃, ZrO₂, Nb₂O₅, and a Ca₃(PO₄)₂ compound (precursor of hydroxyapatite) deposited on the alloy surface, indicating that the presented alloy can stimulate bone formation. The corrosion resistance increased by increasing the sintering temperature and the highest corrosion resistance was obtained at 1200 °C. The improved corrosion protection was found to be related to the alloy densification. The bioactivity and the corrosion resistance of the developed nanostructured alloy in a SBF renders the nanostructured Ti-20Nb-13Zr alloy a promising candidate as an implant material.