Effects of Silicon and Heat-Treatment on Microstructure and Mechanical Properties of Biomedical Ti-39Nb-6Zr Alloy

Abstract

The cytotoxic tissue reactions of alloying elements (Al, V) of Ti-6Al-4V have been reported, whereas the Ti-39Nb-6Zr (TNZ40) alloy developed by adding β-phase stabilizing elements is known to have no cytotoxicity and exhibits excellent biocompatibility. In addition, there is a slight modulus difference between the TNZ40 alloy and human bones as the elastic modulus of the TNZ40 alloy is very low. This can inhibit detrimental effects such as osteoblast loss due to a stress-shielding effect. In this study, various Si contents were added and heat treatment under various conditions was performed to control the microstructure and mechanical properties of the TNZ40 alloy. In the β-type titanium alloy, the ω phase is commonly observed by quenching from the solution-treatment or aging-treatment temperature. These ω precipitates can typically increase the elastic modulus, hardness, and embrittlement of the β-type titanium alloy, which are important to control this phase. The correlation between Si content and precipitation and the effects of solution treatment and aging condition on the mechanical properties such as tensile strength, and hardness, were analyzed.

Effect of Oxygen on Static Recrystallization Behaviors of Biomedical Ti-Nb-Zr Alloys

“…Since the low modulus of elasticity is accompanied by a decrease in strength, it is necessary to study how to improve the compatibility of these opposing properties via microstructure control and mechanical processes. Typical β-Ti alloys have a lower elastic modulus than those of other biomaterials (e.g., stainless steel, cobalt-chrome, and polymer materials), and researchers are actively reporting on the development of β-Ti alloys such as Ti-Nb, Ti-Mo, Ti-Zr, Ti-Ta, and Ti-Nb-Zr that include biocompatible β-stabilizer elements such as Nb, Mo, Zr, and Ta [20][21][22][23][24][25][26][27][28].…”

“…For this study, the Ti-39Nb-6Zr (TNZ40) alloy, which is a β-Ti alloy with a large amount of Nb and Zr content, was selected. This alloy has an elastic modulus of approximately 40 GPa and a single β phase [23,24]. The TNZ40 alloy has better cold formability than α + β Ti alloys, but it has lower strength, and research is needed to resolve this.…”