稀土及杂质元素对ZA27合金晶间腐蚀的影响

Influence of RE and Impurity Elements on the Intergranular Corrosion of ZA27 Alloys

为了从本质上了解杂质与稀土元素对锌铝合金晶间腐蚀的影响 ,探索抑制合金晶间腐蚀的有效途径 ,依据晶界的大角度重位点阵理论编制出相应计算机软件 ,建立含稀土、杂质及 η相颗粒的α相大角度晶界原子集团模型 ,采用递归法计算了α相晶界间的电荷转移 ,由此讨论了杂质 (Pb、Sn、Cd)及稀土元素 (La、Y)对Zn、Al电极电位的影响 .结果表明 ,杂质Pb、Sn、Cd增大原子间的电荷转移量 ,提高Zn、Al电极电位差 ,加速合金的腐蚀 ,稀土元素减小原子间的电荷转移量 ,降低Zn、Al电极电位差 ,具有抑制晶间腐蚀的作用 .

To understand the influence of impurities and rare earth elements in nature on the intergranular corrosion of the zinc-aluminum alloys, taking efficient methods to retard the intergranular corrosion, the atomic cluster of α phase grain boundary including impurities(Pb,Sn,Cd), rare earth elements(La,Y) and η phase grain was constructed by computer programming based on the coincidence-site lattice theory. The recursion method was used to calculate the charge transfer over the grain boundary of α phase, and discuss influence of impurities(Pb,Sn,Cd) and Rare Earth elements(La,Y) on the electrode-potential of Zn and Al. The results shows that impurity elements (Pb,Sn,Cd) can increase the charge transfer between atoms over the grain boundary, leading to the large difference of electrode-potential between Zn and Al. Therefore the eroding is speeding up, but the RE element can reduce the charge transfer between atoms over the grain boundary, and lower the difference of electrode-potential between Zn and Al. Thus RE element is of the role of restraining the intergranular corrosion of zinc-aluminum alloys.