Preparation And Electrochemical Properties Of Biodegradable Mg-based Amorphous Alloys

Magnesium alloys exhibit high potential applying as biodegradable materials due to their low density,biodegradability and good biological activity.However,the traditional magnesium alloy can not meet the effective service period because of the rapid degradation rate,which greatly limits its application in biomedical field.Mg-Zn-Ca amorphous alloys with good biomechanical properties and corrosion resistance are considered to be one of the promising biological materials.However,its degradation rate is still too fast to meet the requirements of biological implants,so it is necessary to take appropriate measures to improve its corrosion resistance.Mg-based amorphous alloys Mg_68-xZn₂₈Ca₄RE_x?RE=Y,La,Dy,x=0,1,3?were prepared by melt spinning and copper-mold casting in this research.The microstructure,thermal stability,glass forming ability and corrosion resistance of the alloys were investigated,and the effects of the addition of rare earth elements on these properties were analyzed.The experimental results are show:?1?By melt spinning and copper-mold casting,Mg-based amorphous alloys Mg_68-xZn₂₈Ca₄RE_x?RE=Y,La,Dy,x=0,1,3?with different sizes were successfully prepared.?2?The glass transition temperature T_g and onset crystallization temperature T_x of Mg_68-xZn₂₈Ca₄RE_x?RE=Y,La,Dy,x=0,1,3?shifted to the direction of high temperature the with the minor addition of rare earth elements,while glass forming ability declined.?3?The polarization curves showed that the corrosion potentials and the polarization resistances of the alloys increased,accompanying with the the decreasing of the corrosion current densities by minor adding rare earth elements.The electrochemical impedance spectra showed that the impedances of the alloys increased with the addition of rare earth elements.It was comcluded that the minor addition of rare earth elements improved the corrosion resistance of Mg-Zn-Ca.?4?X ray photoelectron spectroscopy results showed that the surfaces of the alloys with the minor addition of rare earth elements were enriched with Zn,P,RE,implying that the formation of low solubility phosphate containing Zn,Ca and RE.