中文摘要：

通过计算机软件建立镁合金的晶体，液态及其固／液界面模型。采用递归法计算了稀土元素在a-Mg、固／液界面、镁液态等原子环境中的环境敏感镶嵌能，定义并计算了Mg，La及Y与氧的原子亲和能。计算结果表明：La，Y在镁晶体中的环境敏感镶嵌能较高，不能稳定固溶于晶体中，因此在固体中的溶解度较小。合金凝固时稀土元素扩散到环境能较低的液体中，向液面聚集。由于稀土与氧的原子亲和能低于镁与氧的亲和能（镁、稀土与氧的亲和能分别为Mg-O：-14.9338eV，La-O：-19.0608eV，Y-O：-19.5050eV），聚集在液体表面的稀土将优先与氧结合，生成致密的稀土氧化物，阻止镁合金燃烧。

英文摘要：

The atomic cluster models of a-Mg, liquid Mg and the interface between liquid/solid have been founded by computer program. The environment-sensitive embedding energy of RE elements in a-Mg, liquid Mg, liquid/solid interface has been calculated by recursion method. The atomic affinity energy between Mg, La, Y with O has been defined and calculated. The calculated results show that the solid solubility of La and Y is very small in a-Mg, because their higher environment-sensitive embedding energy leads to instability in a-Mg crystal. The RE elements diffuse to the liquid Mg, which has lower environment-sensitive embedding energy than the solid, and congregate on the surface of liquid Mg as the alloy solidifies. Because the atomic affinity energy of RE-O is lower than Mg-O（The atomic affinity energy between Mg, La, Y with O are Mg-O： -14.9338eV,La-O： -19.0608 eV,Y-O： -19.5050 eV, respectively）, the RE elements congregating on the surface of liquid Mg will priorily combined with O, forming compact RE oxides, which prevent Mg alloys from burning.