The roles of oxygen content on microstructural transformation, mechanical properties and corrosion resistance of Ti-Nb-based biomedical alloys with different β stabilities

Highlights: • This study systematically investigated the roles of oxygen on TiNb alloys with different β stabilities. • The roles of oxygen in stabilizing β need to be manifested under high β stability alloy. • A desirable balance between low Young's modulus and high strength was obtainable by controlling O and Nb content. The effects of oxygen content on phase transformation, mechanical properties and corrosion resistance of TiNb based alloys with different Nb contents (15, 32 and 38 wt%), i.e. different β stabilities were investigated. The results show that the oxygen does not change the phase constitution of α'-type Ti15Nb based alloy with low β phase stability, while the oxygen can suppress the α" martensite and ω phase, acting as β-stabilizer in the higher β phase stability of Ti32Nb and Ti38Nb based alloys. The addition of oxygen increases strength through solid solution strengthening and/or modification of deformation behavior. It has been found that simultaneous improvement in strength and ductility can be achieved in each base alloy by doping a certain content of oxygen. Young's modulus of Ti-Nb-O alloys exhibits different trends with oxygen increasing, which is related to the different effects of oxygen on phase stability. A desirable balance between low Young's modulus and high strength can be obtained through controlling oxygen and Nb content. The Ti-Nb-O alloys exhibit a high degree of corrosion resistance within simulated body fluid (SBF) at 310 K. Particularly, the Ti-38Nb-0.5O alloy exhibits low Young's modulus (52 GPa), high yield strength (1141 MPa) and good elongation (22%), which has potential in biomedical applications.