Effect Of Sm On Microstructure And Corrosion Properties Of AZ80Magnesium

As the lightest metallic constructional material, a magnesium alloy plays a moreand more important role in spaceflight, automobile manufacturing for its high specificstrength, outstanding damping capability and specific stiffness, high heat conductivityand good casting capability and machinability. Unfortunately, magnesium has anumber of undesirable properties including poor corrosion and poor creep resistance,which have hindered its widespread use in many applications.In this paper, rare earth elements Sm were added to AZ80magnesium alloy, tostudy the effect of Sm and second phase on the corrosion properties and mechanicalproperties of AZ80.The effects of rare earth elements Sm addition on the micro-structures, corrosion resistance and mechanical properties of AZ80magnesium alloyswere studied by x-ray diffraction （XRD）, scanning electronic microscope （SEM） andenergy spectrum analysis （EDS）, transmission electron microscope （TEM）, opticalmicroscope, impedance spectroscopy （EIS）, potentiodynamic polarization, immersiontest, Hydrogen evolution test and tensile test. The corrosion process and the effect ofsecond phase were studied by EIS, heat treatment and immersion test with different.The results show that Sm can refine the as-cast microstructure of AZ80, improvethe corrosion resistance and room temperature strength of AZ80within theexperimental range. A new granule structure precipitated phase （Al₃Sm） was found inAZ80-xSm alloys, it could reduce the number of β phase and transform the continuousnet β phase into intermittent distribution ones. When the Sm content in the alloys is0.6%, the corrosion rate in3.5%NaCl neutral solution, was3.3g·m^-2·d^-1, only25%ofthat of AZ80alloy. When add1.0%Sm, the tensile strength and the elongation of thealloy reached213MPa and6.16%, increased by21.7%and18.2%compared with withthe original alloy. So, moderate amount of rare earth Y, Nd addition, can not onlyenhance the AZ80magnesium corrosion resistance, but also do not damage the mechanical performance of it, the comprehensive performance of AZ80magnesiumalloy is improved. Solution treatment can be reduce the corrosion resistance of alloy，After aging treatment the corrosion resistance of the alloy was improved, and thecorrosion resistance of alloy increased by decreasing aging temperature. So, moderateamount of rare earth Sm addition can enhance the corrosion resistance and mechanicalperformance of AZ80magnesium, the comprehensive performance of AZ80magnesium alloy is improved.