The role of heat treatment on microstructure and mechanical properties of Ti–13Zr–13Nb alloy for biomedical load bearing applications

The suitability of heat treated Ti–13Zr–13Nb (TZN) alloy for biomedical load bearing applications has been investigated. Depending upon the heat treatment conditions, the microstructure of TZN alloy mainly consists of αα, ββ or α”α” martensite phases. In general, for all the deformation and solution treatment temperatures the variation of the hardness and tensile strength with cooling rate is similar. The elastic modulus of TZN alloy decreases with an increase in cooling rate from the solution treatment temperature. Relatively fine α+βα+β microstructure increases the hardness and tensile strength. The presence of martensite and/or retained ββ in the microstructure decreases the hardness and elastic modulus and increases the ductility substantially whereas higher amount of αα phase in the matrix increases the elastic modulus. Decomposition of martensite and retained ββ into αα phase during aging increases the hardness, elastic modulus and tensile strength and decreases the ductility. Among the samples studied, the aged TZN sample, which was deformed and solution treated at 800 °C followed by water quenching, is a promising candidate for the application as implant material.