Study On The Microstructure And Corrosion Resistance Performance Of The Medical Deformation Magnesium Alloys

The major drawback of magnesium alloys serving as implant materials is their lowcorrosion resistance in the physiological environment system. Nowadays, alloying and thereasonable deformation and heat treatment process is one of the effective methods to improvethe corrosion resistance of the magnesium alloys.Since Zn, Mn and Ca elements have good biocompatibility, we had fabricated a series ofMg-2Zn-XMn (x=0.2,0.5,1.0) and Mg-2Zn-XCa (x=0.5,1.0) alloys. The effects of theaddition amount of Mn on the microstructure and corrosion resistance property of the Mg-2Znalloy in vitro were investigated. The result indicated that with the addition amount of Mnincreasing, the more second phase precipitate from the α-Mg matrix. The Mg-2Zn-0.2Mnalloy had the best corrosion resistance behavior among the three alloys. The grain size refinedand corrosion resistance improved with Ca element addition in the Mg-2Zn alloy. Comparethe Mg-2Zn-1Ca with the Mg-2Zn-0.5Ca alloy. Due to the amount of the cathode secondphase increased, the corrosion resistance of the former decreased.The effects of the extrusion and heat treatment process on the microstructure andcorrosion resistance of the Mg-2Zn-0.2Mn alloy was studied. Extrusion process cansignificantly refine Mg-2Zn-0.2Mn alloy’s grain. Extrusion and aging treatment can improvethe corrosion resistance of Mg-2Zn-0.2Mn alloy markedly. By the method, its corrosionresistance can be improved.Through the different solidification colling rate, we achieved the Mg-2Zn-0.5Ca alloywith different grain sizes. And we investigated the effects of the different grain sizes on thecorrosion resistance of the Mg-2Zn-0.5Ca alloy. The results of the electrochemical and invitro immerse tests shown that the refine of grain size can improve the alloy’s uniformitycorrosion. It could be explained in terms of the refiner second phase. The amount of thesecond phase which distributed along the grain boundaries, presented as reticulation increased.And, so increased the corrode obstacle function of the alloy. Through the high-speed meltshear mixing process, the Mg-2Zn-0.5Ca-TCP composite materials was be fabricated and theeffects of the equal channel angular pressing (ECAP) on the microstructure and the behaviorwere be studied. Compared with the as-cast alloy, the microstructure of theMg-2Zn-0.5Ca-TCP alloy was more homogeneous, hardness and corrosion resistance wereimproved markedly after the shear extrusion. With the increase of the extrusion pass, the grainrefinement role more obviously, the second phase more homogeneously and the corrosionresistance better.