In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstructural characterization of the as-cast alloys is carried out by X-ray diffraction,optical microscopy and transmission electron microscopy.The results reveal that Nb-containing Ti-Zr alloys transformed from single α phase-α + α" + β phase → single β phase-double β phases with increasing Nb content.In the case of 3-type alloys,the addition of Nb improves the bonding energy between atoms,reduces the grain size,increases the elastic modulus,improves the yield strength and renders superior work-hardening behavior.Moreover,the current study provides mechanistic insights into microstructural evolution and strengthening of Nb-containing Ti-Zr alloys with increasing Nb content.Herein,the addition of 5 at.％ Nb resulted in an abnormal work hardening during compression deformation under the synergistic influence of stress-induced martensite transformation of 3 phase and stress-induced twinning of α phase.Moreover,the biomechanical properties are evaluated to demonstrate the potential of Nb-containing Ti-Zr alloys in biological applications.