Surface characterization of new non-toxic titanium alloys for use as biomaterials

The surface oxide layers formed spontaneously through air contact on three new, non-toxic titanium alloys have been investigated by X-ray photoelectron spectroscopy (XPS). The alloys investigated were Ti–7Nb–6Al, Ti–13Nb–13Zr and Ti–15Zr–4Nb. The results show a large surface enrichment in Al oxides and Zr oxides, respectively, which indicates a considerable outwards diffusion of these two elements. However, an analysis of the Nb 3d spectra reveals that the formation of Nb oxides at the surface is less favoured than in the case of the other alloying elements. The XPS data show for all three Ti alloys a passive layer formed by a mixture of Ti, Al or Zr and Nb oxides.