Effects of Fe and Nb content on microstructure and mechanical characteristics of biomedical Ti based alloys

Abstract

The microstructures and resulting mechanical properties of Ti–xNb–6Zr–7·5Sn–yFe (x=24, 30, 35 and y=1, 2, 2·5 wt-%) alloys were investigated for biomedical application. The microstructures were examined by means of optical microscopy, SEM and X-ray diffraction, and Vickers hardness, compressive elastic modulus and the yield strength have been measured. X-ray diffraction analysis showed that the alloys consist of β+α or β+α+α″ phases. The volume fraction of each phase changes with the variation of Fe and Nb contents according to consulting the relation between the contents of β stabilising elements and phase composition of Ti alloys after quenching from β phase region. The different microstructures result in various mechanical properties of the alloys. Ti–24Nb–6Zr–7·5Sn–2Fe has the higher strength/modulus ratio, i.e. the lower elastic modulus and the higher yield strength; hence, it is more suitable than the other alloys for biomedical applications.