Light weight- low modulus biocompatible titanium alloys processed via spark plasma sintering

Abstract

There is a wide range of biomedical applications for titanium and its alloys due to their biological inertness, excellent biocompatibility, superior corrosion resistance, and little to no adverse reactions. However, the commonly used titanium (Ti-6Al-4 V) alloys have been reported to have high elastic modulus (116 GPa) compared to human bone (10–40 GPa), resulting in bone atrophy caused by stress shielding, a phenomenon of bone degradation caused by an insufficient supply of stress from the implant. The presence of aluminum and vanadium in titanium alloys has also been linked to neurodegenerative diseases like Alzheimer's. A new class of titanium biomedical alloys (Ti-35 Nb-7Zr-5Ta (wt%) also referred to as TNZT alloys) with low toxic alloying elements (niobium, tantalum, and zirconium) and capable of combating the problems associated with Ti-6Al-4 V alloys are being developed. In the present study, various physical, structural, mechanical, and biological properties of such TNZT alloys have been explored, along with their relationship to sintering processing parameters such as sintering temperature (400, 600, 800, and 1000 °C) and sintering pressure (20, 40, and 60 MPa). The sample sintered at 1000 °C demonstrated a single β-phase (BCC) of titanium which clearly indicates that selected sintering temperatures preserve the BCC β-phase in titanium without the formation of the HCP α-phase. Both density and elastic modulus of spark plasma sintered (SPS) TNZT samples increased with increasing sintering pressure and temperature, and the underlying mechanisms were discussed. All the sintered TNZT alloys exhibited excellent biocompatibility and have the potential for use as long-lasting and high-performance biomedical materials.

Keywords

• TNZT alloys
• SPS
• Microstructure
• Elastic modulus
• Density
• Biocompatibility