Research On The Effects Of Rare Earth Elements On The Corrosion Resistance Of AZ80Magnesium Alloy

As the lightest structural metallic materials, Magnesium alloys have excellentproperties such as high specific stiffness and specific strength （density1.738g/cm³）,good electro-magnetic shielding ability, shock absorption properties and heatdispersion, good casting properties and processing properties. Therefore, magnesiumalloys have been extensively applied in automotive, electronics, communication andaircraft industries. However their applications are limited because of the poorcorrosion resistance. It is necessary for industrial applications to study how to improvethe corrosion resistance of magnesium and its alloys. In this paper, trace amounts ofrare earth elements Y and Nd were added to AZ80magnesium alloy respectively,which is as a basic alloy, to study the effect of these rare earth elements on themicrostructure, corrosion properties and mechanical properties of AZ80, and briefdiscussed the mechanism of rare earth improving the corrosion resistance of AZ80magnesium alloy.In this paper, the effects of rare earth elements Y and Nd addition on themicrostructures, corrosion resistance and mechanical properties of AZ80magnesiumalloys were studied by x-ray diffraction （XRD）, scanning electronic microscope （SEM）and energy spectrum analysis （EDS）, optical microscope, potentiodynamicpolarization, immersion test and tensile test. The corrosion property was studied byimmersion test and potentiodynamic polarization.The result indicates: in the experimental range, both Y and Nd can refine the as-cast microstructure of AZ80, improve the corrosion resistance and room temperaturestrength of AZ80. The amount of β-Mg₁₇Al₁₂phase in AZ80alloy decreased sharply,and their morphology changed from continuous network to discontinuous disperseafter the addition of Y and Nd. When Y was added, a new rare earth phase Al2Yarisesed. in3.5%NaCl neutral solution, The optimal modification effect is obtained when the Y content in the alloys was0.5%, the corrosion rate is0.2585mg·cm^-2·d^-1,only the48.07%compared with AZ80alloy. When Nd was added, a new rare earthphase Al₃Nd arisesed. in3.5%NaCl neutral solution, The optimal modification effectis obtained when the Nd content in the alloys was0.2%, the corrosion rate is0.3542mg·cm^-2·d^-1, only the65.87%compared with AZ80alloy. When add0.5%Y, the tensilestrength and the elongation of the alloy were199.29MPa and6.16%, increased by7.49%and7.98%compared with AZ80alloy respectively. When add0.2%Nd, thetensile strength and the elongation of the alloy were190.69MPa and5.66%, increasedby2.90%and2.61%compared with AZ80alloy respectively. So, moderate amount ofrare earth Y, Nd addition, can not only enhance the AZ80magnesium corrosionresistance, but also do not damage the mechanical performance of it, thecomprehensive performance of AZ80magnesium alloy is improved.