ZA27合金中稀土及铁的晶界偏聚与交互作用

根据分子动力学理论建立了液态ZA27合金的原子集团，结合计算机编程构造出ZA27合金α相与液相共存时的原子构形及α相大角度重位点阵晶界模型.利用递归法计算了铁、稀土元素 固溶 于晶粒内，游离于固液相界面及其在α相晶界处的环境敏感镶嵌能，计算了铁、稀土元素与 Al 的键级积分.由此得出：铁、稀土处于固液相界区比在晶内更稳定，解释了铁、稀土在α相内溶解度很小，结晶时富集于固液相界前沿液体中，从而导致凝固结束后铁、稀土元素偏聚于晶界，并形成成分复杂的稀土化合物的事实. 关键词： 稀土 晶界 递归方法 电子结构

Segregation and interaction of rare earth and iron elements on grain boundaries in ZA27 alloys

The model of liquid phase of ZA27 cast alloy was set up in terms of the molecul ar dynamics simulation. The atomic structural models of the α phase liquid int erf ace and the grain boundary of α phase with the coincidence site lattice were c on structed by computer programming. The environment sensitive embedding energy (E S E) of rare earth (or iron) atom in grain, on grain boundary and on α phase liq uid interface was calculated by Recursion method. The bond order integrals (BOI) be tween Fe, RE atom and Al were also computed. The results show that RE and iron e lements are more stable on the α phase liquid interface than in grain, which e xpl ains the fact of very small solid solubility of RE and iron elements in α phase , and the enrichment of RE and iron elements in the solid-liquid growth front whe n solidifying. This leads to the segregation of RE and iron atoms on the grain b oundaries and the formation of the complicated RE compounds.