Nd对车用镀层Zn-5Al-0.2Ti合金组织和耐蚀性的影响

Effect of Nd on Microstructure and Corrosion Resistance of Automobile Coating Zn-5Al-0.2Ti Alloy

采用扫描电镜（SEM）和X射线衍射（XRD）研究稀土Nd对Zn-5Al-0.2Ti合金显微组织和耐蚀性的影响。结果表明：Zn-5Al-0.2Ti合金添加Nd元素能促进α（Al）形核,阻碍η-Zn初生相的生长,提升了合金中的共晶组织含量。随着Nd含量增加,共晶组织平均粒径先降低再增大。当Nd含量等于0.1%时,合金具有最均匀的组织结构和最小平均粒径。随Nd含量增加,合金的耐腐蚀性能先上升后下降。当合金中Nd含量为0.1%时,合金具有最大的极化电阻与最小的腐蚀电流密度,有助于提升共晶组织的均匀性与致密性,获得最优耐蚀性。

The effects of Nd addition on the microstructure and corrosion resistance of Zn-5Al-0.2Ti alloy were investigated by SEM and XRD. The results show that Nd elements addition in Zn-5 Al-0.2 Ti alloy can promote the α（Al）nucleation and hinder the η-Zn growth, which can improve the eutectic content in the alloy. As Nd content increases, the average particle size of eutectic microstructure firstly decreases and then increases. When Nd content is 0.1%, the alloy has the most uniform microstructure and minimum average particle size. With the increase of Nd content, the corrosion resistance of the alloy firstly rises and then falls. When the Nd content in the alloy is 0.1%, the alloy has the largest polarization resistance and minimum corrosion current density, which can improve the uniformity and compactness of eutectic microstructure, and, then, the optimum corrosion resistanc can be obtained.