Microstructure and properties of as-cast Zr-2.5Nb-1X(X=Ru,Mo,Ta and Si) alloys for biomedical application

The micro structure and properties of as-cast Zr-2.5Nb-1X(X=Ru,Mo,Ta and Si) alloy are screened to explore novel biomedical zirconium alloys for magnetic resonance applications.Corresponding micro structure and phase transformation were characterized using X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM).Hardness test,magnetic detection and electrochemical corrosion measurements are taken to present properties.The results show that all alloys consist of α-Zr,β-Zr and ω-Zr.α-Zr and β-Zr mainly exist in the form of parallel and intersecting plates,and nanoscale ω-Zr is dispersed in β-Zr plate.Especially,blocky ω-Zr with needle-like α-Zr is only found in plate-free blocks of Zr-2.5Nb-1Mo/Ru alloy.The orientation relationship(OR) between α-Zr and ω-Zr follows [1120]_α//[1101]_ω and(0001)_α//([1011]_ω 011)_ω.Combining this OR with the OR between β-Zr and ω-Zr,the transformation relationship between β-Zr/ω-Zr and α-Zr is also discussed.Zr-2.5Nb-1Ru alloy with high corrosion potential(-0.500 V),low corrosion rate(0.949 μm·year^(-1)) and low magnetic susceptibility(92×10^(-6)) shows great potential to be a novel biomedical implant with magnetic resonance imaging compatibility.Based on the experimental results,the possible relationship among alloying elements,micro structure and properties has been established in these Zr-2.5Nb-1X alloys.