Cold rolling deformation and annealing behavior of a β-type Ti-34Nb-25Zr titanium alloy for biomedical applications

In this study, the microstructures and mechanical properties of a newly developed β-type Ti-34Nb-25Zr (TNZ) alloy after cold rolling at different reduction ratios and recrystallization annealing were investigated by optical microscopy, XRD, SEM, EBSD, hardness and tensile tests. The tensile strength of the TNZ alloys reached 1071 MPa after cold rolling, which is 1.4 times the tensile strength of the solution-treated alloy. The deformation mechanisms of the TNZ alloys were significantly affected by the cold rolling reduction ratio (CRRR). The dominant deformation mechanisms for the TNZ alloys cold rolled at 20% and 56% CRRR were the formation of kink bands and of stress-induced α" martensite. With increases in CRRR to 76%, the TNZ alloys showed a combination of deformation mechanisms including the formation of shear bands and stress-induced α" martensite, and {332} <113> β mechanical twinning. The TNZ alloy after cold rolling at 86% CRRR followed by annealing exhibited elongation at rupture of 18%, tensile strength of 810 MPa, Young's modulus of 66 GPa, and toughness of 132 MJ/m3, making it attractive for biomedical applications.