A study of mechanical and magnetic properties in a metastable Zr–10Nb–6Sn alloy for MRI-compatible hard tissue replacements

Abstract

In this study, we presented an investigation into a newly developed metastable Zr–10Nb–6Sn alloy meticulously tailored to fulfill the demanding requisites of magnetic resonance imaging (MRI)-compatible hard implants. The effect of cold rolling reduction (0%, 10%, 20% and 40%) on the mechanical properties and magnetic susceptibility of the alloy has been systematically studied. With the increase of cold rolling reduction, the yield strength and tensile strength of the alloy increase, while the elastic modulus decreases first and then increases slightly. The sample with 40% cold rolling (CR40%) exhibits excellent matching of yield strength ∼ 905 MPa and elastic modulus ∼55.8 GPa, with a superior yield strength-to-elastic modulus ratio than that of other reported metallic biomedical materials. The deformation mechanism of Zr–10Nb–6Sn alloy during cold rolling includes stress-induced α'' phase, kink bands and dislocation slip. Due to the addition of Sn element with low magnetic susceptibility (0.03× 10−6 cm3g−1) and the formation of ω phase, the solution-treated sample (CR0%) has a low magnetic susceptibility ∼ 0.77 × 10−6 cm3g−1, which is significantly lower than that of other reported titanium and zirconium based biomedical alloys. The magnetic susceptibility of the samples increases from 0.77× 10−6 cm3g−1 to 1.35 × 10−6 cm3g−1 as the cold rolling reduction increases, which may be attributed to the decrease in ω-phase content and the increase in α''-phase content during cold rolling. Hence, the cold-workable Zr–10Nb–6Sn alloy, exhibiting exceptional mechanical compatibility and low magnetic susceptibility, holds promise as a potential alloy for MRI-compatible hard tissue replacements.

Keywords

• Metastable Zr alloy
• Biomaterials
• Low magnetic susceptibility
• Low elastic modulus
• High strength