中文摘要：

利用大角重位点阵模型,建立了镁合金[0001]对称倾斜晶界原子集团,应用实空间的连分数方法计算了合金元素铝在晶界的偏聚能,晶界处铝原子间相互作用能和不同体系的费米能级,讨论了铝在晶界的偏聚行为,铝原子间的相互作用与有序化的关系及镁合金晶间应力腐蚀的物理本质。计算结果表明：铝原子偏聚于晶界,且主要偏聚于晶界的原子密集区;铝原子间相互排斥,因此在晶界区形成有序相;有序相的费米能级低于镁晶粒,其腐蚀电位较高,构成镁晶粒的腐蚀原电池的阴极,在应力作用下,使镁合金发生晶间应力腐蚀。

英文摘要：

By using the coincidence-site lattice model （CSL）,the atomic structure of symmetric [0001] tilt boundary of phase in Mg alloy has been set up.The segregation energies of alloy element Al, the interaction energies between AI atoms and Fermi energy levels of different systems have been calculated by using recursion method.The Al segregation behavior at the grain boundaries, the relationship between the interaction among Al atoms and the ordering tendency, as well as the physical nature of the stress corrosion of Mg alloy have been discussed.Calculating results show that：Al atoms segregate to GB, and are easy to occupy the sites of the compressed region of GB.Al atoms repel each other,therefore form ordered phases in the region of GB.The Fermi energy of ordering phase is lower than that of Mg alloy grain, the corrosion electric potential level is higher than Mg alloy grain,so the ordering phase becomes the cathode of Mg alloy corrosion primary cell, which makes the Mg alloy corrode along grain boundaries under tension stress.