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Obtaining and microstructualand mechanical characterization of Ti-Nb-Sn alloys applied as biomaterial

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Author(s):
Giorgia Taiacol Aleixo
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Mecânica
Defense date:
Examining board members:
Rubens Caram Junior; Itamar Ferreira; Celia Marina de Alvarenga Freire; João Batista Fogagnolo; Marcelo Falcão de Oliveira
Advisor: Conrado Ramos Moreira Afonso; Rubens Caram Junior
Abstract

This work deals with preparation, processing and microstructural and mechanical characterization of ß type Ti-Nb-Sn alloys aiming the manufacturing of orthopedic devices for implants. Ti samples containing Nb at levels of 25, 30 and 35 wt % and Sn at levels of 2, 4 and 8 wt % were prepared by arc melting, homogenized at 1000ºC/8 h and plastically deformed by swaging. These samples were submitted to continuous cooling experiments to evaluate conditions for obtaining metastable phase. Then, samples heated to 1000ºC were rapidly cooled and analyzed by using differential scanning calorimetry and X-ray diffraction at medium temperatures, which allowed the evaluation of martensite decomposition. Next, samples in the ß field were air-cooled, which resulted in microstructures with a phase precipitated into ß matrix. These samples were characterized concerning the microstructure by applying optical, scanning electron and transmission electron microscopies and X-ray diffraction, while the mechanical behavior was evaluated by Vickers hardness test, elastic modulus measurement using acoustic techniques, tensile and fatigue tests. The results obtained indicate that martensite decomposition results in ß, ? and finally a phases. It was also found that ? phase acts as substrate for a phase nucleation. The sample mechanical behavior directly depends on the phases present in the microstructure, as well as their volumetric fraction. It was also observed that elastic modulus, hardness and tensile strength of air cooled samples show higher values than those of rapidly quenched samples, while ductility decreases. Finally, it was observed that fatigue resistance of air cooled samples is higher for low Nb content alloys, however, it decreases with Sn addition (AU)

FAPESP's process: 05/04402-0 - Obtainment, microstructural and mechanical characterization of Ti-Nb-Sn alloys applied in orthopedic implants
Grantee:Giorgia Taiacol Aleixo
Support Opportunities: Scholarships in Brazil - Doctorate