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镧铈(La,Ce)混合稀土的添加改变了AZ91镁合金微观组织和元素分布。La元素与Ce元素在AZ91镁合金中以不同的形式存在,一部分固溶在镁合金基体中,一部分参与生成了针状的Al4(La,Ce)相和粒状的Al_(10)Ce_2Mn_7相。稀土添加后AZ91镁合金中β相的体积分数有所降低,Al元素分布由晶界向晶内迁移。对不同添加量的稀土镁合金在模拟融雪剂溶液中的干湿交替循环腐蚀行为的研究结果表明,La、Ce混合稀土的添加,可以增加镁合金表面膜的致密度。虽然混合稀土降低了镁合金的自腐蚀电位,但腐蚀电流密度相比较于AZ91明显降低。SECM结果则表明,稀土添加可以减少镁合金表面微区的活性点数量。
The addition of lanthanum cerium (La, Ce) mixed rare earth changed the microstructure and elemental distribution of AZ91 magnesium alloy. La element and Ce element exist in different forms in AZ91 magnesium alloy, some of them are solid solution in the matrix of magnesium alloy, and partly participate in the formation of acicular Al4 (La, Ce) phase and granular Al_ (10) Ce_2Mn_7 phase. The volume fraction of β phase in AZ91 magnesium alloy decreases after rare earth addition, and the distribution of Al element shifts from the grain boundary to the intragranular. The results show that the addition of La and Ce mixed rare earths can increase the density of the surface film of magnesium alloy. Although the mixed rare earth reduces the corrosion potential of the magnesium alloy, the corrosion current density is obviously lower than that of AZ91. SECM results show that the addition of rare earth can reduce the number of active sites in the surface area of magnesium alloy.