Sn对铸态AZ91镁合金抗腐蚀性能的影响

Effect of Sn on Corrosion Resistance of As-cast AZ91 Magnesium Alloys

摘要: 利用金相显微镜、X-射线衍射、扫描电镜、集气法和电化学测试研究了铸态AZ91+xSn （x=0,0.2,0.5,1wt%）镁合金的显微组织和腐蚀行为。结果表明，实验合金在3.5% NaCl溶液中浸泡时，随着Sn含量的增加，其抗腐蚀性能先提高后降低。AZ91+0.2Sn合金具有最小的腐蚀速度，为AZ91合金的54%，主要是完全离异共晶β-Mg₁₇Al₁₂相替代了AZ91合金中的部分离异共晶β-Mg₁₇Al₁₂相；但AZ91+1.0Sn合金具有最大的腐蚀速度，为AZ91合金的118%，这是因为此合金具有局部腐蚀。

Abstract: The microstructure and corrosion behavior of AZ91+sSn（x =0,0.2,0.5,1wt%） magnesium alloys were investigated by optical microscopy（OM）, X-ray diffractometry（XRD）, scanning electron microscopy（SEM）, collecting gas method and electrochemical test. The results show as following:with Sn addition increasing, the corrosion resistance of tested alloys initially improves and then decreases in 3.5%NaCl solution. The AZ91+0.2Sn alloy has the lowest corrosion rate, which is 54% of AZ91 alloy, is contributed to the fully divorced β-Mg₁₇Al₁₂phase in the alloy replacing the partially divorced β-Mg₁₇Al₁₂ phase in AZ91 alloy. Nevertheless, AZ91+1.0Sn alloy has the highest corrosion rate, which is 118% of AZ91 alloy,is ascribed to the existence of located corrosion in the alloy.