RESUMO
New generation titanium alloys with low elastic moduli are promising materials for medical implants, particularly load-bearing orthopaedic implants. In this paper, the effect of niobium content on the microstructure and mechanical properties of new Ti alloys including Ti-23Nb-7Zr, Ti-28Nb-7Zr and Ti-33Nb-7Zr (wt%) is studied. Ti-23Nb-7Zr was found to mainly form αÎ and αâ³- phases, while both the Ti-28Nb-7Zr and Ti-33Nb-7Zr consisted of αâ³ and ß-phases with an increased amount of ß-phase in the alloy with 33â¯wt% of Nb. X-ray diffraction and microstructural analyses showed that the addition of Nb stabilises the ß-phase in the solution treated condition with the depleting amount of αÎ and αâ³- phases. The hardness and Young's modulus values were highest in Ti-23Nb-7Zr which is attributed to the high fraction of αÎ- phase in this alloy. The Young's moduli achieved for the three alloys through nanoindentation were 35.9, 29.1 and 29.0â¯GPa, respectively. The new alloys are encouraging candidates for orthopaedic implants due to their low elastic modulus which can help inhibit stress shielding, although biocompatibility tests (in-vitro and in-vivo) are suggested for future work.
