Design and fabrication of a metastable β-type titanium alloy with ultralow elastic modulus and high strength

Titanium and its alloys have become the most attractive implant materials due to their high corrosion resistance, excellent biocompatibility and relatively low elastic modulus. However, the current Ti materials used for implant applications exhibit much higher Young's modulus (50 similar to 120 GPa) than human bone (similar to 30 GPa). This large mismatch in the elastic modulus between implant and human bone can lead to so-called "stress shielding effect" and eventual implant failure. Therefore, the development of beta-type Ti alloys with modulus comparable to that of human bone has become an ever more pressing subject in the area of advanced biomedical materials. In this study, an attempt was made to produce a bone-compatible metastable beta-type Ti alloy. By alloying and thermomechanical treatment, a metastable beta-type Ti-33Nb-4Sn (wt. %) alloy with ultralow Young's modulus (36 GPa, versus similar to 30 GPa for human bone) and high ultimate strength (853 MPa) was fabricated. We believe that this method can be applied to developing advanced metastable beta-type titanium alloys for implant applications. Also, this approach can shed light on design and development of novel beta-type titanium alloys with large elastic limit due to their high strength and low elastic modulus.