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Microstructural evolution and mechanical properties of metastable beta titanium alloys in the Ti-Nb-Fe system

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Author(s):
Fernando Henrique da Costa
Total Authors: 1
Document type: Master's Dissertation
Defense date:
Advisor: Rubens Caram Júnior
Abstract

The use of titanium and its alloys as engineering materials had greatly increased during the second half of the twentieth century. This growth is due to the development of new titanium alloys with improved mechanical properties. Among titanium alloys, ß metastable alloys present a wide range of mechanical properties which make them interesting for industry in general, as these alloys allow combinations of 'alpha' and ß phases in different ratios and morphologies, depending on the processing route used. A promising form of treatment for these alloys involves aging at ß +'alpha' phase field in order to obtain intragranular homogeneous 'alpha'-phase precipitates. In this work, ß metastable Ti-Nb and Ti-Nb-Fe alloys were studied. Different temperatures and heating rates were evaluated in order to determine their influence during 'alpha' phase precipitation. The characterization of these alloys was made using thermal analysis technique, X-ray diffraction, optical microscopy, scanning electron microscopy and Vickers hardness analysis and elastic modulus measurements. The results obtained show that the presence of 'omega' phase significantly raises the hardness of the alloys. The highest hardness values were found in samples aged at 400 °C, temperature at which allowed better detection of this phase by X-ray diffraction. At aging temperatures corresponding to lower hardness values (at 550 °C), no 'omega' phase peaks were found in X-ray diffraction patterns. The addition of 1 % wt. Fe allowed finer 'alpha' phase precipitation (AU)

FAPESP's process: 13/13867-2 - Microstructure Evolution and Properties of Metastable Beta Titanium Alloys of the Ti-Nb-Fe Alloys
Grantee:Fernando Henrique da Costa
Support type: Scholarships in Brazil - Master