稀土对ZA27合金晶间腐蚀影响的电子理论研究

通过自行开发的计算机软件构造了ZA27合金中α相大角度晶界析出η相及稀土元素的原子集团模型. 采用递归法计算了Al, Zn, La, Y的局域态密度, 计算并分析了α相、η相的总态密度和费米能级, 及稀土对态密度和费米能级的影响. 计算表明: 稀土元素的局域态密度形状与Zn相近, 其与Zn结合的能力大; 稀土元素降低η相的费米能级, 减小Zn, Al电极电位差, 具有抑制晶间腐蚀的作用; 稀土元素不改变α相、η相的总态密度形状, 但使η相的态密度增大, 改变η相的电子结构; 晶格结构对原子的态密度有一定的影响, 掺杂原子的态密度趋于与基体原子态密度相同.

Electronic Theory Study on the Influence of Rare Earth Elements on the Intergranular Corrosion of ZA27 Alloys

The atomic cluster model of α phase of ZA27 high angle grain boundary including rare earth elements (La, Y) and η phase was constructed by self-developed computer programm. Recursion method was used to calculate the local density of states of Al, Zn, La and Y elements, and the total density of states and Fermi level of α phase and η phase. The influence of rare earth elements (La, Y) on the density of states and Fermi level was discussed. The calculated results show that: the local density of states of RE element are similar to that of Zn, so RE element can combine with Zn easily; RE element can reduce the Fermi level of η phase, lower the difference of electrode-potential between Zn and Al, so RE element is of the function to restrain the intergranular corrosion of zinc-aluminum alloys; RE element can not change the shape of total density of state of α and η phase, but can heighten the total density of state of η phase, and change the electronic structure of η phase; the crystal structure have effect on the atomic density of states, the density of state of impurity atom go tends to be similar with that of matrix atom.