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Hardening Mechanism through Phase Separation of Beta Ti-35Nb-7Zr-5Ta and Ti-35Nb-7Ta Alloys

Published online by Cambridge University Press:  16 November 2012

C. R. M. Afonso*
Affiliation:
Universidade Federal de São Carlos (UFSCar), Departament of Materials Engineering (DEMa), 13565-905, São Carlos - SP, Brazil.
P. L. Ferrandini
Affiliation:
State University of Campinas (Unicamp), Department of Materials Engineering (Dema/FEM), CEP 13083-970, Campinas - SP, Brazil
R. Caram
Affiliation:
State University of Campinas (Unicamp), Department of Materials Engineering (Dema/FEM), CEP 13083-970, Campinas - SP, Brazil
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Abstract

The β titanium alloys are highly attractive metallic materials for biomedical applications due to their high specific strength, high corrosion resistance and excellent biocompatibility, including low elastic modulus. The aim of this work is the evaluation of hardening mechanism through phase separation in β Ti-35Nb-7Zr-5Ta (TNZT) and Ti-35Nb-7Ta (TNT) alloys. Ingots (50 g) of TNZT and TNT alloys were arc-furnace melted in Ar(g)atmosphere. XRD using synchrotron radiation together with TEM and HRTEM analysis showed the coexistence of two separated phases (β and β’) with similar crystalline structures and slightly different lattice parameters in TNZT and TNT alloys. It was detected a heterogeneous microstructure alternating nanosized dark and bright regions (∼10 nm) with different compositions (Nb-rich β and Ta-Zr-rich β’).In aged condition (400ºC/4h), TNZT and TNT alloys undergoes coherent spinodal decomposition of β phase into two solid solution phases with coherent interface, different compositions and elastic strain associated with nanometric domains of Nb-rich β and Ta-(Zr)-rich β’ phases.

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Articles
Copyright
Copyright © Materials Research Society 2012 

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