ZA27合金晶界处铁、稀土元素的有序化与交互作用

Ordering and interaction of Fe and RE atoms on grainboundaries in ZA27 Alloys

为从理论上揭示铁、稀土元素在锌铝合金晶界处的行为本质,建立了ZA27合金中α相大角度重位点阵晶界模型,利用递归法(Recursion)计算了晶界的电子结构(状态密度、费米能级、结构能).用晶界结构能定义合金的团簇能(有序能),并计算了偏聚铁及稀土晶界的团簇能.计算结果表明:铁、稀土元素在锌铝合金晶界处团簇能为正值,不能形成团簇,具有有序化倾向,趋于形成稳定的金属间化合物.铁与稀土元素在晶界形成负电中心,降低晶界的费米能级.

In order to reveal the behaviors of Fe and RE atoms on grain boundaries in ZA27 alloy theoretically, the atomic structure model of high angle grain boundary of a phase in ZA27 alloy was set up by using the concept of coincidence-site lattice（CSL）. The electronic structure （state density, Fermi energy level, structure energy） of grain boundary was calculated using the recursion method. The clustering energy of alloying atoms was defined by the structure energy of grain boundary, and the clustering energies of Fe or RE atoms on grain boundary was calculated. The calculated results show that： the clustering energy of Fe or RE atoms gathered on grain boundary in ZA27 alloys is positive, so they can not form clusters and have the ordering tendency. Fe and RE atoms prefer to form steady inter-metallic compounds, and can form the negative electricity center on grain boundary in ZA27 alloys, thus reducing the Fermi energy level of grain boundary.