High strength, low modulus and biocompatible porous Ti–Mo–Fe alloys

Abstract

Porous Ti–10Mo–xFe (x = 2–5) alloys were prepared by powder metallurgy using ammonium hydrocarbonate (NH4HCO3) as the space-holder. When 7 wt% NH4HCO3 is added, the porosity of the Ti–Fe and Ti–Mo–Fe alloys is about 20 %. It was found that Fe has a significant strengthening effect on the Ti-based alloys, while Mo is effective in stabilizing the Ti–10Mo–xFe alloys into β-phase. The inherent better ductility of β-phase than that of the α-phase and the efficient strengthening effect Fe provide a good combination of strength and ductility to the Ti–10Mo–xFe alloys. The compressive yield strength of the porous Ti–10Mo–xFe alloys is from 500 to 800 MPa, much higher than that of the Fe–10Mo alloy (about 260 MPa) and human bone (about 130–180 MPa). Elastic modulus of the alloys is <10 GPa. The alloys also have corrosion resistance similar to that of pure Ti. Cytotoxic tests show that the L929 cell RGR values of the Ti–10Mo–xFe alloys are over 80 % at day 1, day 4 and day 7. The cells grew in good condition on the seventh day. The results indicate that the porous Ti–10Mo–xFe alloys have superior mechanical properties, good corrosion resistance, and excellent biocompatibility, and are promising candidates for bone substitute materials.