Effect of Titanium Addition on the Structure, Microstructure, and Selected Mechanical Properties of As-Cast Zr-25Ta-xTi Alloys

Pedro Akira Bazaglia Kuroda,Barbara Letícia Tomaz Pedroso,Fenelon Martinho Lima Pontes,Carlos Roberto Grandini

doi:10.3390/met11101507

Pedro Akira Bazaglia Kuroda, Barbara Letícia Tomaz Pedroso + Show 2 more

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https://doi.org/10.3390/met11101507

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Abstract

Ti alloys are the most used metallic materials in the biomedical field due to their excellent biocompatibility associated with good corrosion resistance in body fluids and relatively low elastic modulus. However, the alloys used in the orthopedic area have an elastic modulus that is 2 to 4 times higher than that of human cortical bone. Searching for new alloys for biomedical applications and with low elastic modulus, zirconium gained prominence due to its attractive properties, especially its biocompatibility. The purpose of this paper is to present novel as-cast alloys of the Zr-25Ta-xTi system and analyze the influence of titanium on the structure, microstructure, microhardness, and elastic modulus of the alloys. The alloys were prepared using an arc-melting furnace. X-ray diffraction measurements and microscopy techniques were used to characterize the crystalline structure and microstructure. From structural and microstructural characterizations, it was observed that titanium acted as an α-stabilizing element since its increase in the precipitation of the orthorhombic α” phase, an intermediate phase from β to α phases, in the alloys. Regarding microhardness measurements, the alloys have higher hardness than pure zirconium due to solid solution hardening that detaches the Zr-25Ta alloy, which has a high hardness value of the precipitation of the ω phase. Among the studied alloys, the Zr-25Ta-25Ti alloy is highlighted, demonstrating the lowest result of modulus of elasticity, which is approximately 2 times higher than the human cortical bone, but many alloys used in the biomedical field, such as pure titanium, have elastic modulus values almost 3 times higher than that of human bone.

Highlights

As technology advances and quality of life increases, the demand for metallic biomaterials for use as orthopedic and dental implants increases
Zirconium and titanium belong to the IVB group in the periodic table
Besides having good mechanical properties compared to stainless steel and Co-Cr alloys [23], zirconium alloys have good corrosion resistance, good biocompatibility in body fluids, and their implantation in bone tissue induces the formation of a small bone apatite layer on their surfaces [1]

Summary

Introduction

As technology advances and quality of life increases, the demand for metallic biomaterials for use as orthopedic and dental implants increases. Zirconium and titanium belong to the IVB group in the periodic table They are known to have a similar structure and chemical properties [22], enabling the study of zirconium alloys for biomedical applications. Besides having good mechanical properties compared to stainless steel and Co-Cr alloys [23], zirconium alloys have good corrosion resistance, good biocompatibility in body fluids, and their implantation in bone tissue induces the formation of a small bone apatite layer on their surfaces [1]. Zirconium is an element that has an allotropic transformation at a temperature of 862 ◦ C, where below this temperature, its crystalline structure is hexagonal compact (α phase) This temperature, its crystalline structure is body-centered cubic (phase β) [24]. Tantalum has a body-centered cubic crystal structure, a weak β-stabilizer element, and is often used to control the titanium alloys’ structure and microstructure [26]

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