Effect of Oxygen Content on Microstructure and Mechanical Properties of Biomedical Ti-29Nb-13Ta-4.6Zr Alloy under Solutionized and Aged Conditions

The effect of oxygen content on the microstructure and mechanical properties of the Ti-29 mass%Nb-13 mass%Ta-4.6 mass%Zr (TNTZ) alloy was investigated in this study. The microstructural observation of TNTZ alloys, containing 0.1-0.4 mass% oxygen, subjected to solution treatment shows the presence of a single phase. With an increase in oxygen content, the hardness, tensile strength, and Young's modulus of TNTZ alloy increase, but its elongation decreases. Further, the a phase precipitates in TNTZ alloys subjected to aging treatment at 723 K for 259.2 ks. The results of transmission electron microscopy and X-ray diffraction analysis indicate that the size and volume fraction of the a phase increase with oxygen content. Corresponding to the changes in the microstructure. the mechanical properties of TNTZ alloy subjected to aging treatment at 723 K change with oxygen content. The increase in oxygen content leads to enhancement of the age hardening of TNTZ alloy, thereby increasing both tensile strength and Young's modulus of TNTZ alloy, but its elongation decreases due to the a-phase precipitation. The mechanical properties of TNTZ alloy (Young's modulus: around 60-100 GPa, tensile strength: around 600-1400 MPa, and elongation: around 5-25%) vary significantly depending on oxygen content and heat treatment. [doi: 10.2320/matertrans.MA200904]