Influence of Thermal Treatment on the Microstructure, Mechanical Properties, and Corrosion Resistance of Newly Developed Ti20Nb13Zr Biomedical Alloy in a Simulated Body Environment

Abstract

The effect of thermal treatments on the microstructure, hardness, and electrochemical performance in a simulated body fluid were studied for the newly developed (β + α) Ti20Nb13Zr alloy (TNZ) for biomedical applications. The alloy was heat-treated for 1 h at 900 °C and then cooled at different cooling rates. Then, the solution-treated samples were aged at 400, 500, or 600 °C for 5 h. The phase evolution and microstructure of the treated alloy were examined using XRD and SEM/EDX analysis. The mechanical properties were assessed using microindentation. The surface protection performance against corrosion was assessed by potentiodynamic polarization and electrochemical impedance spectroscopic analysis. The obtained results showed that the wide range of microstructure with varied volume fraction and morphology of β and α were obtained with different heat treatment conditions. The different phases’ sizes and distributions influenced the microstructure obtained during the heat treatment, thereby affecting the mechanical properties. The corrosion performance significantly altered with variations in the microstructure of the TNZ alloy as a result of the different thermal treatments. The heat treatment of TNZ conferred enhanced combination of mechanical and corrosion protection compared to that of the commercial Ti6Al4V alloy.