Study On A New Technique Of Surface Treatment Of AZ31 Magnesium Alloy

At present,a lot of researches have been done on the treatment of magnesium alloy at home and abroad,and also have made much headway,but there still exist some problems,which are poor combination,pollution and high cost.Therefore,the new technology on the treatment of magnesium alloy of high performance,energy saving,environmental protection,low cost needs to be studied and popularized.In this paper,a new technology of high energy grinding and isothermal heat treatment is studied,the process makes the metal powder in a semi molten state,which is formed infiltration layer on the surface of AZ31 magnesium alloy.And comprehensive analysis of the influence of surface treatment process and different milling time,different powder and different powder addition order on the infiltration layer.The surface macro morphology,layer thickness,composition distribution,phase composition and corrosion resistance of the infiltrated layer are analyzed by using scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS),X-ray diffraction(XRD)and electrochemistry workstation.The results show that the new technology can form a continuous and dense infiltration layer on the surface of the magnesium alloy,and the thickness was increased with the increase of high energy milling time.The thickness of infiltration layer can reach 95?im.The infiltration layer is mainly composed of Al,Zn,Mg,Mg7Zn3 and a small amount of Mg17Al12,and there is no crack and gap between the infiltration layer and the magnesium alloy.The results of corrosion tests show that the self corrosion potential of infiltration layer is increased by about 2 times than AZ31 magnesium alloy.Place the treated magnesium alloy in the natural environment about one year,however,there is no corrosion on the surface of the treated samples.The best process parameters:grinding time of 90min,mixing Aluminum and zinc powder mixed by 2:1(9g),isothermal heat treatment temperature of 350?,the holding time of 9h.In conclusion,it can form infiltration layer by high energy milling metal powder and heat preservation process,and can improve the surface properties and broaden the application fields of magnesium alloy.Compared with the traditional process,the method used in this paper is simple,low cost and environmental protection,and also has a certain practical value and a good prospect for industrial application.