Mechanical Properties and the Microstructure of β Ti-35Nb-10Ta-xFe Alloys Obtained by Powder Metallurgy for Biomedical Applications

Titanium alloys with high refractory metals content are required to obtain advanced biomaterials with a low elastic modulus and good mechanical properties. This work studies the influence of Fe content on the microstructure and mechanical properties of powder metallurgy Ti35Nb10Ta(Fe) alloys, with Fe content additions of 1.5, 3.0 and 4.5 wt%. Samples are obtained by uniaxial compaction and sintering at 1250 degrees C and 1300 degrees C. Microstructural characterization is performed by scanning and transmission electron microscopy and mechanical characterization by bending, compression and a hardness test. The elastic modulus is measured by the ultrasounds technique. The results show a 10% increase in the maximum bending strength with an increase in the sintering temperature. The obtained microstructure is composed of beta-Ti phase (bcc) and some regions where laths of the alpha-Ti (hcp) phase occur along the grain boundaries. Fe addition slightly improves the stability of the beta-Ti phase and conversely decreases the maximum strength and final deformability due to increased porosity. The Ti35Nb10Ta alloy composition displays better properties, with an elastic modulus of 75 GPa, a bending strength of 853 MPa and compression strength of 1000 MPa.