Evaluation of the influence of low Mg content on the mechanical and microstructural properties of β titanium alloy

Abstract

It was investigated in order to better understand the relationship between the low presence of Mg in the Ti–Nb–Sn alloy in its mechanical and microstructural properties by the powder metallurgy technique for biomedical application. The blended powders with the nominal composition of Ti–34Nb–6Sn were obtained by milling at 200 rpm/40 min, compacted at 200 MPa. The sintering were carried out at 900 °C/2 h and at 1110 °C/2 h, followed by furnace cooling. The particle size was characterized by the dynamic image analyzer (DIA). The phases quantification and their microstructure were characterized by an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The porosity was characterized by the Archimedes method and also bi-dimensionally by the Image J software. The mechanical tests were performed by the impulse excitation (Sonelastic ®) technique, in order to evaluate the elastic modulus (E) of the sintered materials and the hardness and resistance by the Rockwell method. The results indicated that the sintering at 1100 °C in the materials with Mg, still had particles of Nb not diffused. The microstructure was basically formed by two phases with the presence of Nb non-diffused in all conditions except at 1100 °C in the system without Mg. The β phase % for systems without and with Mg at 900 °C was approximately 80% and 65%. At 1100 °C, 76% and 78%. The E and hardness were 31 GPa and 226 MPa at 900 °C; 49 GPa and 344 MPa at 1100 °C for materials with Mg. The O and N content increased approximately 1.3 times when adding Mg powder.