Microstructure, Elastic Modulus and Tensile Properties of Ti-Nb-O Alloy System

In the present study Ti-Nb binary alloy system was chosen because it has excellent biocompatibility as well as reasonable mechanical properties, aiming at understanding oxygen content on microstructural formation,elastic modulus and tensile properties in Ti-Nb alloy system. Small alloy buttons of 50 mm in diameter were prepared by arc melting on a water-cooled copper hearth under an argon gas atmosphere with a non-consumable tungsten electrode. The button ingots were then heat treated in a vacuum atmosphere at 1273 K for 0.5 h followed by water quenching in a specially designed heat treatment furnace. Microstructure, elastic modulus and tensile properties were investigated in order to understand the effect of oxygen content in quenched TiNb alloy system. The orthorhombic structured α″ martensite was changed to bcc structured β-phase with increasing Nb content. Interestingly, it was found that oxygen makes β-phase stable in quenched Ti-Nb alloy system. Elastic modulus values were sensitive to phase stability of constituent phases. Yield strength increased with increasing oxygen content. Details will be explained by phase formation and stability behavior.