Gd对Mg-Zn表面膜与腐蚀特性的影响研究

Influence of Gd on the surface film and corrosion characteristic of Mg-Zn alloy

采用砂型铸造工艺制备Mg-1Zn和Mg-1Zn-2Gd镁合金试样,采用EDS对试样表面的元素分布情况进行测试。测试结果表明,添加Gd后,在合金表面随深度增加氧原子含量迅速下降,Gd元素在表面聚集,使得合金表面的氧化膜致密度比较高,具有较强的保护作用。对全浸腐蚀后的Mg-1Zn-2Gd合金表面进行SEM分析,发现合金表面发生局部腐蚀,第二相的不连续分布导致其主要作为阴极相起加速腐蚀的作用,但其腐蚀阻挡作用依然存在。

The magnesium alloy samples were prepared by sand casting process.EDS is used to test elements distribution on the surface.The results show that after the addition of Gd,the percentage of oxygen atom reduces rapidly,and the accumulating of element Gd on the surface makes the surface film become dense.The SEM was also adopted for the surface observation of Mg-Zn-2Gd alloy after corrosion.The results indicate that local corrosion occurrs.The discontinuous distribution of second phase mainly acts as cathode to increase the corrosion rate.But the second phase still acts as corrosion barrier layer.