Obtention of bio-alloy Ti-30Nb-4Sn via powder metallurgy

This work deals with the preparation, processing, microstructural and mechanical characterization of Ti-30Nb-4Sn alloys, aimed at a future biomaterial manufacture for use as orthopedic implants. Samples were prepared via powder metallurgy and sintered at 1200ºC, 1250ºC and 1300ºC and cooled inside the oven itself, that is, heated in β field followed by slow cooling. Following this procedure, it was obtained a microstructure with the α phase precipitated in the matrix of β Ti, that means an alloy of (α + β) type. These samples were characterized with regard to microstructure by optical microscopy, scanning electron microscopy, confocal microscopy and X-ray diffraction, while the mechanical behavior was assessed by means of Vickers hardness and microhardness tests, abrasion test, for determination of the linear Wear Index (LWI), and compression tests, in order to evaluate the elastic modulus and the yield stress. To complete the characterization, titanium, niobium and tin powders were mixed in the right proportions and subjected to differential scanning calorimetry (DSC) tests, which allowed the alloy behavior evaluation, during heating and cooling cycles. The obtained results show that the alloy is composed by the α and β phases and martensitic phases α' and α''. The mechanical behavior of the samples depends, directly, on the present phases in the microstructure as well as the sintering temperature. It was also found that the density, the porosity and the roughness, as well as the elastic modulus, hardness, microhardness and LWI, showed respective variations, in results, depending on the sintering temperature, and they point to the sintering temperature of 1300ºC as the best result. Finally, it was observed that the presented results confirm the literature review, achieve the proposed objective and indicate Ti-30Nb-4Sn alloy like a possible application as orthopedic implant device. (author)