Design And Mechanism Of Mg-Zn Based Medical Alloys

The research and development of medical metal implant materials is rapidly advancing from the direction of bioinert to bioactive and functional.With its unique performance advantages,Mg-based alloys have become a research hotspot in the field of medical metal implant materials.However,the high corrosion rate of common Mg-based alloys in body fluids will affect the tissue activity,resulting in insufficient mechanical strength before tissue repair.Therefore,the systematic design of Mg-based alloys is expected to improve the comprehensive medical performance,realize the absorption controllability,ensure the integrity of implant devices in the early stage of rehabilitation treatment,and can be completely absorbed in the healing period.In this work,Mg-Zn-based medical alloys with Sr and Ag elements were investaged,and the crystal structure and mechanical properties of Mg11-xZnxSr phase were systematically studied.Rietveld refined data showed that Mg11-xZnxSr phase belonged to the tetragonal 141/amd space group and had the Cd11Ba prototype.With the increase of Zn content,the lattice parameters of Mg11-xZnxSr phase decreased stably,while the elastic constants,bulk modulus,shear modulus and Young’s modulus increased.It was determined that Mg11-xZnxSr can be used as a strengthening phase in Mg or Zn-based alloys,which is of great significance for the development of medical alloys containing Sr.The amorphous forming ability of Mg-Zn-Ag ternary alloy glass and the corrosion behavior of the prepared Mg-Zn-Ag and Mg-Zn-Sr amorphous alloys were studied in this work.In the composition close to Mg67Zn29Ag4(at.%),the maximum Trg is 0.525,which has the best glass forming ability,and the maximum Ep value was obtained in this composition,indicating that it is the best amorphous alloy with the best thermal stability.The corrosion rate of Mg-Zn-Ag amorphous alloys is lower than the recommended value(0.5mm/year).The concentration of Mg ions and pH value in SBF solution of different Mg-Zn-Ag amorphous alloy samples increase with the extension of soaking time.The cell compatibility test of Mg-Zn-Ag amorphous alloys with lower corrosion rate was carried out.It reveals the possibility of its biomedical application.The mechanical properties of Mg-Zn-Ag crystalline alloys with three components after extruded processing were analyzed.The ultimate tensile strength and tensile yield strength of extruded Mg-Zn-Ag alloy samples were higher than 290Mpa and 210Mpa respectively,which could meet the clinical requirements of magnesium alloy in the process of bone implantation(yield strength greater than 200MPa).