The Biodegradable Performance Of Mg-based Amorphous Alloys

More and more attention has been paid to the biological research on magnesium alloysdue to its low density and biodegradable property. However, the currently availablemagnesium alloys still encounter difficuities during their application. For example, thebiodegradable rate of magnesium alloys is faster than that of bone healing rate. In addition,magnesium alloys exhibit low mechanical properties, which easily causes subsequentimplant failure. Therefore, seeking new type of Mg alloys is always important. Mg-basedamorphous alloys exhibit great improvement in mechanical properties and corrosionresistance as compared to the conventional Mg alloys, which shows high promising inbiological application.In this work, the Mg66-xZn30Ca4Mx(M=Y, Nd, Zr and Ce; x=0,0.5,1and1.5at.%)amorphous alloys were fabricated by the single roller spinning method. The effects of traceelements Y, Nd, Zr and Ce on the microstructure and properties of Mg-Zn-Ca amorphousalloy system were investigated by the electrochemical measurements, the X-ray diffraction(XRD), scanning electron microscope (SEM) coupled with electron dispersive X-rayspectroscopy (EDS), and fourier transform infrared spectroscopy (FTIR). The experimentalresults show as follows:(1) The melt-spun of magnesium alloys are amorphous alloys. The electrochemicalproperties of the samples exhibit that the corrosion potentials of the Mg-Zn-Ca-M(M=Y,Nd Zr, Ce) alloys increase with addition of M elements. The SEM images show that thecorrosion products increase gradually with the extension of immersion time in simulatedbody fluid (SBF), which is consistent with the results of FTIR.(2) It is observed that the surface morphologies of the alloys immersed in SBF for7days change with the M additions. A layer of compact structure is formed on the surface ofMg65Zn30Ca4Y1, which effectively prevents the invasion of SBF solution and then improvesthe corrosion resistanc of alloys. However, The flake-like structure of vertical to the alloysubstrate is formed on the surface of1.5at.%Y-containing alloy immersed in SBF for7days. This structure makes the corrosion resistance of the Mg-Zn-Ca-Y alloys decrease. Onthe other hand, the flake-like structure of parallel to the alloy substrate is formed on thesurface of1.0at.%Nd-containing and1.5at.%Zr-containing alloys immersed in SBF for7days. This structure could prevent the corrosion fluids against the new matrix effectively,which enhances the corrosion resistance of the alloys. Among all the trace elements, Ceelement is the most effective element for improving the corrosion resistance. Moreover,almost no surface morphology changes are observed for the Mg-Zn-Ca alloy containing Ce element after immersion in SBF, indicating the Mg-Zn-Ca-Ce alloys exhibit highestcorrosion resistance.