Study On Microstructure And Corrosion Resistance Of Mg-Zn-Ca Alloy And Mg-Zn-Ca Alloy

Magnesium alloy has unique advantages over other medical metal materials,but due to the faster degradation rate,It has been widely limited in the field of medical metal materials.Many studies on corrosion resistance have been carried out on as-cast magnesium alloys with added zinc and calcium elements,while there are few studies on the corrosion resistance of magnesium-zinc-calcium alloys after hot extrusion deformation treatment.Based on the above analysis and research,this article designed and melted Mg-3Zn-xCa（x=0,0.5,1,1.5 wt.%）Alloy,after hot extrusion treatment,analyzed the microstructure of extruded alloy with different Ca addition The corrosion mechanism in simulated body fluids and 3.5%NaCl solution was discussed with the influence of corrosion degradation behavior.On the basis of this composition,adding 4%rare earth yttrium element,using zinc as a variable,preparing hot-extruded Mg-4Y-1Ca-xZn（x=0,1,3,5 wt.%）Alloy,analysis The effect of different Zn additions on the microstructure and corrosion degradation behavior of the extruded alloy was discussed in terms of its corrosion mechanism in simulated body fluids and 3.5%NaCl solution.The main results are as follows:（1）With the increase of Ca content,the Ca₂Mg₆Zn₃phase is produced in the extruded Mg-3Zn-xCa（x=0,0.5,1.0,1.5）alloy.As the Ca content increases further,the Mg-3Zn-1.5Ca The Mg₂Ca phase is produced in the alloy.In the simulated body fluid and 3.5%NaCl solution,the corrosion law is roughly the same.With the increase of Ca content,the corrosion resistance increases first and then decreases.The alloy with Ca content of 1 wt.%Has the best corrosion resistance.Although the grains of the alloy with a Ca content of 1.5wt.%Are refined,a large amount of fine and uniform low-potential Mg₂Ca phases are produced,the number of primary cells is greatly increased,and the corrosion resistance is the worst.（2）The extruded Mg-3Zn-xCa（x=0,0.5,1.0,1.5）alloy in 3.5%NaCl solution has obvious low-frequency induced arc resistance,indicating that the surface film of the sample in this solution The destruction and the generation of Mg²⁺are faster than that in the simulated human fluid,which is closely related to the difference in the chloride ion concentration between the two media.（3）In the extruded Mg-4Y-1Ca alloy containing no Zn element,other than the Mg₂Ca phase,no other second phase was detected.As the Zn content increases,the grain size decreases,and Mg₃Y₂Zn₃（W phase）and Mg₁₂YZn（X phase）are simultaneously formed.In the simulated body fluid and the 3.5%NaCl solution,the corrosion law is roughly the same.With the increase of the Zn content,the corrosion resistance in the simulated body fluid and the 3.5%NaCl solution is slightly improved.As the Zn content further increases,the amount of Mg₃Y₂Zn₃（W phase）increases and the corrosion resistance decreases.In 5Zn alloy,Mg₃Y₂Zn₃（W phase）is in the form of broken small particles,which can play a certain role in protecting the substrate after the corrosion products are produced,and the corrosion resistance is slightly improved.