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Development and characterization of new alloys of the Ti-Ta-Zr system for biomedical applications

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Pedro Akira Bazaglia Kuroda
Total Authors: 1
Document type: Doctoral Thesis
Press: Bauru. 2020-01-31.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências. Bauru
Defense date:
Advisor: Carlos Roberto Grandini

Titanium and alloys currently are used as implants possessing excellent corrosion resistance and mechanical properties more suited to stainless steel implants and Co-Cr. The titanium alloy used for most biomedical applications is Ti-6Al-4V, however studies showed that vanadium and aluminum are harmful to human health. The objective of this study was to prepare Ti-25Ta-Zr system alloys, where the zirconium content was varied from 0 to 75 % in weight, and to analyze the influence of zirconium substitutional solute in the structure, microstructure, hardness and elastic modulus. At the same time, several annealing, lamination and solubilization treatments were carried out to modify the phases, structures, microstructure and elastic modulus of the materials. The chemical characterization of materials was performed by energy-dispersion spectroscopy, inductively coupled plasma optical emission spectrometry, gas analysis, and density measurements. The structural analysis was performed by x-ray diffraction measurements. Microstructural analysis was performed by optical, scanning and transmission electron microscopy. To verify the initial biocompatibility of the alloys, cytotoxic tests were performed. A preliminary analysis of the mechanical properties of the alloy was obtained by means of microhardness and dynamic elastic modulus measurements. The chemical composition results showed that the samples produced are of good quality, close to proposed stoichiometry. The results showed the coexistence of α, α’, α”, β e  phases, depending of zirconium content and thermomechanical treatment done and, that zirconium helped the β phase stabilization. Solubilization heat treatments are capable of modifying the phases present in the samples and, treatments performed at low temperatures, induced α” phase precipitation; treatments performed at high temperatures induced β phase retention and, slow cooling treatments promoted α phase diffusion. The hardness and elastic modulus values of the alloys are changed by increasing the zirconium content. Hardness increases due to solid solution hardening and the elastic modulus decreases due to β phase stabilization. No cytotoxic effects were observed in all produced alloys. (AU)

FAPESP's process: 15/09480-0 - Development and Characterization of new Alloys of the Ti-25Ta-Zr system for Biomedical Applications
Grantee:Pedro Akira Bazaglia Kuroda
Support Opportunities: Scholarships in Brazil - Doctorate