In this study, the activities of binary alloys (Sn-Ag, Sn-Cu, Sn-Zn, Ag-Cu, Ag-Zn, Cu-Zn) and ternary alloys (Sn-Ag-Cu, Sn-Ag-Zn, Sn-Cu-Zn) were predicted using molecular interaction volume model (MIVM), modified MIVM (M-MIVM), Wilson equation, and nonrandom two-liquid model. The prediction deviations of the M-MIVM were the smallest among the four thermodynamic models, indicating that the M-MIVM is reliable for predicting the activity of these multicomponent lead-free solders. On this premise, the activities of all components in ternary Sn-Ag-Cu solders at 1300 K were predicted using the M-MIVM. We found that the activities of Sn, Ag and Cu exhibit negative deviations from Raoult’s law and that these deviations eventually transform into positive deviations. The activities of all components in quaternary Sn-Ag-Cu-Zn solders at 1000 K were also predicted using the M-MIVM when Zn contents were 0.1 and 0.2. This study provides a complete thermodynamic description of Sn-Ag-Cu ternary and Sn-Ag-Cu-Zn quaternary alloys.

在本研究中，二元合金（Sn-Ag、Sn-Cu、Sn-Zn、Ag-Cu、Ag-Zn、Cu-Zn）和三元合金（Sn-Ag-Cu、Sn-Ag-Zn、 Sn-Cu-Zn) 使用分子相互作用体积模型 (MIVM)、改进的 MIVM (M-MIVM)、Wilson 方程和非随机两液体模型进行预测。M-MIVM 的预测偏差在四个热力学模型中最小，表明 M-MIVM 对预测这些多组分无铅焊料的活性是可靠的。在此前提下，使用 M-MIVM 预测了 1300 K 三元 Sn-Ag-Cu 焊料中所有组分的活性。我们发现 Sn、Ag 和 Cu 的活性表现出与 Raoult 定律的负偏差，并且这些偏差最终会转化为正偏差。当Zn含量为0.1和0.2时，使用M-MIVM还可以预测1000 K下的季Sn-Ag-Cu-Zn焊料中所有组分的活性。本研究提供了 Sn-Ag-Cu 三元合金和 Sn-Ag-Cu-Zn 四元合金的完整热力学描述。