中文摘要：

合金形成焓是确定合金的稳定性及其非晶形成能力的重要因素。采用Miedema理论和几何外推模型相结合,预测了Al-Cu-RE（RE=La~Lu）体系液态合金整个成分范围的混合焓。计算结果表明：Al-Cu-RE三元体系的混合焓比Al-Cu二元合金的混合焓更负,稀土元素与Al、Cu之间的化学势差对混合焓的贡献起主要作用。当铝与稀土元素含量相同时,随着铜含量的减少,合金混合焓越来越负,从而表明在Al-Cu合金中加入稀土元素有利于Al-Cu-RE三元合金的形成。同时较负的混合焓是合金体系易于非晶化的重要条件之一,也说明Al-Cu-RE三元体系非晶形成能力较强。计算了Al8Cu4RE和Al Cu RE等三元化合物的形成焓,计算得到的Al Cu RE的形成焓比相应的Al8Cu4RE的形成焓要负,说明Al Cu RE更稳定;同时计算了金属间化合物Al（Cu1-xREx）3、Al（Cu1-xREx）、Al2（Cu1-xREx）的形成焓随稀土含量变化趋势。计算结果为Al-Cu-RE体系非晶形成的成分设计和相关性能研究提供了重要的热力学数据。

英文摘要：

The formation enthalpy is very important for the stability and amorphous forming ability of alloys. A method based on the Miedema＇s theory and the geometric model was used to calculate the mixing enthalpies of liquid Al-Cu-RE（RE=La~Lu） alloys. The calculated results indicate that the mixing enthalpies for Al-Cu-RE ternary alloys are more negative than those of Al-Cu liquid alloys, which arises from chemical potential differences between the rare earth elements and Al, Cu. The maximum for the magnitude of mixing enthalpies for Al-Cu-RE liquid systems increases with the decrease of composition of Cu. It means that the addition of rare earth element is beneficial to the stability and amorphous forming ability for Al-Cu-RE systems. The formation enthalpies of intermetallics Al Cu RE and Al8Cu4 RE were also calculated. The formation enthalpy of Al Cu RE is more negative than that of Al8Cu4 RE. The formation enthalpies as a function of composition of rare earth elements for Al（Cu1-xREx）3, Al（Cu1-xREx） and Al2（Cu1-xREx） were also calculated. The obtained formation or mixing enthalpies could be useful for the investigations of amorphous forming abilities and composition design of Al-Cu-RE alloys.