Low springback and low Young’s modulus in Ti29Nb13Ta4.6Zr alloy modified by Mo addition

Abstract

Deformation-induced higher Young’s modulus can satisfy the contradictory requirements of Ti alloys for spinal-fixation applications, which demand a high Young’s modulus to reduce springback during operations and a low Young’s modulus to prevent stress shielding effect for patients after surgeries. In this study, TNTZ(1, 3, 5)Mo are designed by adding Mo and Ti to Ti29Nb13Ta4.6Zr (TNTZ) in order to maintain low initial Young’s modulus and achieve low springback. All the solutionized alloys show single ¢ phase with increasing the ¢ stability by Mo addition. They show low Young’s moduli less than 65 GPa, similar ultimate tensile strength of 650 MPa and elongation around 20%. The springback of TNTZ3Mo and TNTZ5Mo is lower than that of TNTZ and TNTZ1Mo owing to their more stable ¢ phase. After cold rolling, TNTZ3Mo shows the largest increasing ratio of 25% in Young’s modulus and the highest ultimate tensile strength owning to the appearance of deformation-induced ½ phase. With the low initial Young’s modulus of 59 GPa, TNTZ3Mo is a potential candidate to make the spinal rods in spinal fixation devices.