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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。
The formation of alloy enthalpy is to determine the stability of the alloy and amorphous formation of an important factor. The Miedema theory and the geometric extrapolation model were used to predict the enthalpy of mixing in the whole composition range of Al-Cu-RE (RE = La-Lu) liquid alloy. The results show that the enthalpy of mixing in Al-Cu-RE ternary system is more negative than that of Al-Cu binary alloy. The chemical potential difference between REE and Al and Cu plays an important role in the enthalpy of mixing. When the contents of aluminum and rare earth elements are the same, the enthalpy of mixing is more and more negative with the decrease of copper content, which indicates that the addition of rare earth elements to Al-Cu alloy is beneficial to the formation of Al-Cu-RE ternary alloy. At the same time, the more negative enthalpy of mixing is one of the most important conditions for the easy amorphization of the alloy system. It also shows that the Al-Cu-RE ternary system has a strong amorphous formation ability. The formation enthalpies of ternary compounds such as Al8Cu4RE and Al Cu RE were calculated. The calculated formation enthalpy of Al Cu RE was negatively correlated with the formation enthalpy of Al8 Cu4 RE, which indicated that Al Cu RE was more stable. Meanwhile, the intermetallic compounds Al (Cu1 -xREx) 3. The formation enthalpies of Al (Cu1-xREx) and Al2 (Cu1-xREx) vary with the content of RE. The calculated results provide important thermodynamic data for the compositional design and related properties of the amorphous Al-Cu-RE system.