Microstructures and mechanical properties of metastable Ti-30Zr-(Cr, Mo) alloys with changeable Young's modulus for spinal fixation applications.

In order to develop a novel alloy with a changeable Young's modulus for spinal fixation applications, we investigated the microstructures, Young's moduli, and tensile properties of metastable Ti-30Zr-(Cr, Mo) alloys subjected to solution treatment (ST) and cold rolling (CR). All the alloys comprise a β phase and small athermal ω phase, and they exhibit low Young's moduli after ST. During CR, deformation-induced phase transformation occurs in all the alloys. The change in Young's modulus after CR is highly dependent on the type of deformation-induced phase. The increase in Young's modulus after CR is attributed to the deformation-induced ω phase on {3 3 2} mechanical twinning. Ti-30Zr-3Cr-3Mo (3Cr3Mo), which exhibits excellent tensile properties and a changeable Young's modulus, shows a smaller springback than Ti-29Nb-13Ta-4.6Zr, a β-type titanium alloy expected to be useful in spinal fixation applications. Thus, 3Cr3Mo is a potential candidate for spinal fixation applications.