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Influence of thermo-mechanical processing on structure and mechanical properties of a new metastable β Ti–29Nb–2Mo–6Zr alloy with low Young's modulus

par Vieira Nunes, Aline Raquel;Borborema, Sinara;Araújo, Luana L.S.;Malet, Loïc ;Dille, Jean ;Henrique de Almeida, Luiz
Référence Journal of alloys and compounds, 153078
Publication Publié, 2019-02-01

Article révisé par les pairs

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Résumé :

A low Young's modulus is required for titanium alloys used in orthopedic implants, such as hip prosthetic stems, in order to avoid stress shielding due to a large difference in Young's modulus between the prosthetic stem and the cortical bone. The low Young's modulus has been observed to occur in metastable β-Ti alloys by precipitation of a stress-induced α″ martensite during cold deformation. Under this context, the Influence of thermo-mechanical processing on the microstructure and mechanical properties of the metastable β Ti–29Nb–2Mo–6Zr alloy was studied as well as the influence of the degree of deformation by cold rolling with subsequent annealing after homogenization heat treatment. The alloy presents a β microstructure after solution heat treatment at 1000 °C for 24h, followed by water quenching, while posterior cold rolling induces the precipitation of α” martensite. Young's modulus decreases and hardness increases with the degree of deformation. The annealed samples showed higher hardness and Young's modulus than the cold rolled samples. A thickness reduction of 90% maximizes the hardness/Young's modulus ratio and optimizes the required mechanical properties for orthopedic implants. The results indicate that the alloy is a promising alternative for the widely used Ti–6Al–4V.