Microstructure and Corrosion Resistance of Powder Metallurgical Ti-Nb-Zr-Mg Alloys with Low Modulus for Biomedical Application

Abstract

Due to the bioinert nature, titanium alloy shows poor bone-implant integration and insufficient osseointegration in vivo . In this study, a series of low elastic modulus bioactive titanium alloys with a nominal composition of Ti-13Nb-13Zr-1.25Mg (wt.%) were prepared using mechanical alloying and spark plasma sintering techniques. The microstructures, mechanical properties, degradation behaviors and in vitro bioactivities of these alloys were systematically investigated. The α-Ti, β-Ti and Nb (Zr)-rich phases were found in the alloy sintered at 700℃, and Mg was uniformly distributed in the alloy. In addition to above-mentioned phases, α" phase was found in the alloys sintered at 800℃ and 900℃. It is worth noting that the density, elastic modulus, ultimate compressive strength, yield strength and corrosion resistance of the alloys revealed an increased trend with increasing sintering temperature. The alloy sintered at 900℃ exhibited high density, good compressive strength and excellent corrosion resistance, and showed lower elastic modulus (~69 GPa) than that of biomedical Ti–13Nb–13Zr alloy (~80 GPa). In vitro experiments showed that the alloys sintered at 800℃ and 900℃ promoted cell adhesion and proliferation. However, the alloy sintered at 700℃ inhibited cell proliferation, which was induced by the higher Mg 2+ concentration released from the alloy. Thus, the optimally-processed Ti-Nb-Zr-Mg alloy sintered at 900℃ shows immense potential as a biomedical material.

Keywords: Powder metallurgy, Low modulus, Ti-Nb-Zr-Mg alloy, Corrosion resistance, Bioactivity