Corrosion behaviour and surface modification of the β-type biomedical Ti-24Nb-4Zr-8Sn alloys

The low modulus beta-type Ti-24Nb-4Zr-8Sn alloy is a promising new biomedical alloy due to its excellent mechanical biocompatibility and composition of non-toxic elements. As a biomaterial, to determine its suitability for body implant applications, the important aspect is the evaluation of corrosion behaviour and the establishment of a suitable surface state in terms of a tailored surface topography and chemistry which improves corrosion resistance and enables an optimum osseointegration of bone tissue. The goal of this review is to summary the corrosion properties of Ti-24Nb-4Zr-8Sn alloy in the basic human body environments. Meanwhile, the surface modification technology which is emphasised on surface nanocrystallisation and micro-arc oxidation are systematically discussed, the former has been confirmed to be an effective way to improve the stability and pitting resistance of Ti-24Nb-4Zr-8Sn alloy, especially in the fluoride ions containing environments; whereas the later not only increases the corrosion resistance of Ti-24Nb-4Zr-8Sn alloy, but also induces the formation of apatite on the surface to exhibit good bioactivity.