Phase transformations and mechanical properties of a Ti36Nb5Zr alloy subjected to thermomechanical treatments

Various solid state phase transformations exist in metastable β-type Ti alloys,which can be employed to optimize the mechanical properties.In this paper,synchrotron X-ray diffraction(SXRD)experiments were carried out to study the phase transformations of a Ti36Nb5Zr alloy subjected to different thermomechanical treatments.Furthermore,the correlation between the phase constitutions and the mechanical properties was discussed.The a" texture formed,and high-density defects were introduced after cold rolling of the solution treated specimen,leading to the decrease in Young’s modulus and the increase in strength.The cold-rolled specimens were then annealed at temperatures from 423 to 773 K for 30 min.Both the Young’s modulus and strength increased with annealing temperatures increasing up to 673 K,which resulted from the precipitation of the ω and/or α phases.With further increase in annealing temperatures to 773 K,the β→α precipitation replaced the β→ω_(iso) phase transformation,and the density of defects decreased,leading to the decrease in both the Young’s modulus and strength.These results provide theoretical basis for the design biomedical Ti alloys with both low Young’s modulus and high strength.