Tensile and fatigue evaluation of Ti-15Al-33Nb (at.%) and Ti-21Al-29Nb (at.%)alloys for biomedical applications

In this work the fatigue and tensile behavior of Ti-15 Al-33Nb (at.%) and Ti-21 Al-29Nb (at.%) was evaluated and compared to that for other titanium-based biomedical implant alloys, in particular Ti-6Al-4V (wt.%). The mechanical properties of interest were fatigue strength, tensile strength elastic modulus, and elongat ion-to-failure. Fatigue stress versus life curves were obtained for tests performed at room temperature in air as well as in Ringer´s solution at R=0,1 for maximum stresses between 35% and 90% of ultimate tensile strength. The results indicated that the fatigue strength and lives and elastic modulus of these alloys is comparable to that for Ti-6Al-4V (wt.%). Considering the data scatter and deformation behavior, the Ringer´s solution did not significantly affect the fatigue behavior. Heat treatment reduced the tensile strength and this corresponded to a reduction in the fatigue strength. The tensile strength of the as-processed Ti-A l-Nb alloys was slightly lower than that for Ti-6Al-4V (wt.%) and the Ti-15Al-33 Nb (at.%) exhibited lower strength and higher elongations than Ti-21Al-29Nb. Based on the current results, it is proposed that titanium- aluminium-niobium alloys will be of considerable future interest for biomedical applications.