A metastable β-type Ti-Nb binary alloy with low modulus and high strength

Abstract

With the assistance of thermo-mechanical treatment, an attempt was made to fabricate a simple binary Ti-38Nb (wt.%) alloy with low modulus and high strength. The martensitic transformation from β to α″ occurred in the solution-treated Ti-38Nb alloy, resulting in low yield strength. Upon a cold rolling plus annealing at 673 K for 40 min, a lot of dislocations and grain boundaries were introduced in the Ti-38Nb alloy, which played key roles in inhibiting the martensitic transformation and retarding the precipitation of ω. Therefore, overwhelming β phase with low content of β-stabilizers can survive at room temperature, giving rise to a low modulus of 56 GPa. Meanwhile, the Ti-38Nb alloy was remarkably reinforced, with a yield strength of 850 MPa and a ultimate tensile strength of 1020 MPa, because of the inhibition of α″ martensitic transformation. As a result, the cold rolled plus annealed Ti-38Nb alloy can exhibit higher strength-to-modulus ratio than those of the current implant materials and thereby has high potential applications in hard tissue replacements.