Effects of Y Element on Microstructure and Corrosion Resistance of As-Cast Mg-Al-Ca-Mn-Y Alloy
The microstructure and corrosion resistance of as-cast Mg-4Al-3Ca-0.7Mn-xY(x=0,0.8,1.5)alloys were investigated by metallographic microscope,scanning electron microscope,XRD,corrosion test and electrochemical test.The results show that the microstructure of Mg-4Al-3Ca-0.7Mn alloy without Y is composed of α-Mg,Al2Ca and Mg2Ca phases.After adding 0.8wt%Y,the grains in the microstructure of the alloy are obviously refined,and the precipitation phase is fine.The number of Al2Ca and Mg2Ca phases is reduced,and the Al2Y phase is formed.When Y content increases to 1.5wt%,the grain refinement effect is not obvious,and a large amount of Al2Y phase aggregate in a network distribution at grain boundaries.The corrosion resistance of Mg-4Al-3Ca-0.7Mn-xY alloy can be improved by adding appropriate Y element.The corrosion resistance of the alloy is best when the addition amount of Y is 0.8wt%.
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