An analytical model is developed to calculate the segregation behavior of a micro-alloying element to the liquid/liquid interface and its effect on the liquid/liquid interfacial energy during the solidification of a monotectic alloy based on the thermodynamics of alloys. Experiments are carried out with Al-Bi alloy micro-alloyed by different elements. The model is verified by the experimental results. Calculation results demonstrate that, for an A-B monotectic system, the segregation behavior of the micro-alloying element i depends on the partition coefficient K_i (ratio of the mole fraction of i in the B-rich melt to that in the A-rich melt), which is closely related to the atomic interaction energy parameters L_A-i for the A-i binary alloy, L_B-i for the B-i binary alloy, L_A-B for the A-B binary alloy. A simple but efficient criterion is proposed based on K_i for choosing the interface active element i for the A-B monotectic alloy: K_A < K_i < K_B.

基于合金的热力学，开发了一个分析模型来计算微合金化元素在液/液界面的偏析行为及其对偏晶合金凝固过程中液/液界面能的影响。对不同元素微合金化的Al-Bi合金进行了实验。通过实验结果验证了该模型。计算结果表明，对于 AB 偏晶系统，微合金元素i的偏析行为取决于分配系数K _i （ i在富 B 熔体中的摩尔分数与在富 A 熔体中的摩尔分数之比), 与原子相互作用能参数L _{A-密切相关i}为A- i二元合金， L _{B- i}为B -i二元合金， L _A-B为AB二元合金。一个简单而有效的准则被提出基于K _i来选择AB 偏晶合金的界面活性元素i ： K _A < K _i < K _B。