TEM–EDX Study of Process of Apatite Formation on Bioactive Ti–6A1–4V Alloy in Simulated Body Fluid

Bioactive Ti–6A1–4V alloy, prepared by NaOH and heat treatments, forms a bonelike apatite layer on its surface in the body, and bonds to bone through this apatite layer. In this study, the process of apatite formation on the alloy in a simulated body fluid (SBF) was investigated by transmission electron microscope. It was found that the Ti–OH groups formed on the alloy via exchange of Na+ ions with H3O+ ions, induce apatite formation indirectly by forming an amorphous calcium titanate and an amorphous calcium phosphate. The formation of the calcium titanate and calcium phosphate are proposed to be the results of electrostatic interactions between the Ti–OH groups and the calcium and phosphate ions in SBF.