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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α-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.
The crystal, liquid and solid / liquid interface model of magnesium alloy were established by computer software.The environment-sensitive inlaid energy of rare earth elements in α-Mg, solid / liquid interface and magnesium liquid were calculated by recursion method The atomic affinity between Mg, La, Y and oxygen was calculated. The calculated results show that La and Y have high environmental sensitivity in magnesium crystal, which can not stably dissolve in the crystal. Therefore, the solubility in solid is low. Rare earth elements diffuse into the liquid with lower environmental energy and solidify to the liquid surface during the solidification of the alloy.As the atomic affinity between rare earth and oxygen is lower than that of magnesium and magnesium (the affinity energies of rare earth and oxygen are Mg-O: -14.9338 eV, La-O: -19.0608 eV, YO: -19.5050 eV). The rare earths accumulated on the surface of the liquid will preferentially combine with oxygen to form a dense rare earth oxide and prevent the magnesium alloy from burning.