Effect of Oxygen Content on Microstructure and Mechanical Properties of Ti-29Nb-13Ta-4.6Zr Alloy for Biomedical Applications

Abstract

The effect of oxygen content on the microstructure and mechanical properties of Ti-29Nb-13Ta-4.6Zr (TNTZ) solutionized and aged at 723 K was investigated. The microstructure of solutionized TNTZ consists of a single β phase, and addition of oxygen leads to the increase in the hardness and tensile strength because of solid solution hardening, and the increase in Young's modulus, and the decrease in the elongation. On the other hand, the α phase precipitates in the aged TNTZ. The results of transmission electron microscopy and X-ray diffraction imply that the size and volume fraction of the α phase increase with the oxygen content in the aged TNTZ. The mechanical properties of the aged TNTZ change with the oxygen content. Age hardening in aged TNTZ is enhanced by an increase in the oxygen content. Further, with an increase in the oxygen content, both the tensile strength and Young's modulus increase, while elongation decreases due to the precipitation of the α phase. TNTZ with different mechanical properties (Young's modulus: around 60-100 GPa, tensile strength: around 600-1400 MPa, elongation: around 5-25%) can be obtained depending on the oxygen content and the heat treatment technique.