Effects of Pb on microstructure, mechanical properties and corrosion resistance of as-cast Mg97Zn1Y2 alloys

In this present work, Pb was applied in the Mg97Zn1Y2 alloy to improve its microstructure and properties, using conventional casting methods. The microstructure and properties of the Mg97Zn1Y2 alloy and Mg97Zn1Y2-xPb(x=0.6wt.%, 1.2wt.% and 1.8wt.%) alloys were observed by optical microscopy, scanning electron microscopy method and analyzed by X-ray diffraction, hardness and strength measurement and electrochemical testing. After adding Pb to the Mg97Zn1Y2 alloy, a new particle phase Mg2Pb was identified along the grain boundaries, and dendrites were refined. In addtion, the hardness of Mg97Zn1Y2-xPb(x=0.6wt.%, 1.2wt.% and 1.8wt.%) alloys was higher than that of the Mg97Zn1Y2 alloy; with the increase of Pb content, the hardness of the alloy increased first and then decreased, followed by a final slight increase, and reached a maximum of 89.1 HV when the Pb content was 0.6wt.%. The strength of the alloy increased first and then decreased as the Pb content increased. Moreover, adding a small amount of Pb to the alloy can effectively inhibit corrosion, and Mg97Zn1Y2-0.6wt.%Pb exhibits the best corrosion resistance ability.