The mixing enthalpies for liquid Ba–Sn alloys were determined by isoperibolic calorimetry at 1300 K over the entire composition range. Large exothermic mixing effects ( ∆Hmin = –54.8 ±± 1.8 kJ/mole at xBa = 0.56) were found. They are indicative of strong interaction between different components and of short ordering in the liquid alloys. The thermochemical properties of the melts and barium stannides and the phase equilibria in the Ba–Sn system were used to calculate the activities of components, molar fractions of associates, and formation enthalpies and entropies for liquid BaxSn1–x alloys with the ideal associated solution (IAS) model. Two associates, BaSn and Ba2Sn, were selected for the calculation. The calculated activities of components in the Ba–Sn melts show very large negative deviations from the ideal solution, which is consistent with their thermochemical properties. The maximum concentration of each associate is approximately 0.65 for respective compositions. The calculated formation enthalpies for BamSnn intermetallics are quite high exothermic values that agree well with the published data for BaSn3 and only qualitatively for Ba2Sn. The formation enthalpy for the associate agrees with that for the respective BaSn intermetallic and is slightly less exothermic for Ba2Sn. This all indicates that the bonding energies between different atoms in the respective intermetallics and melts are close to each other and quite high. The formation entropy for the Ba2Sn associate is lower and that for BaSn is higher in magnitude. This demonstrates different degrees of ordering in BaSn and Ba2Sn associates and intermetallics. This may be due to different changes in the oscillation frequencies of atoms and other factors. The calculated liquidus curve of the Ba–Sn phase diagram agrees with data for the Sn–Sr system.

中文翻译：

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Ba-Sn合金的热力学性质和相平衡

液态 Ba-Sn 合金的混合焓是通过等周量热法在 1300 K 下在整个组成范围内确定的。发现了大的放热混合效应（ΔHmin = –54.8 ±± 1.8 kJ/mole，xBa = 0.56）。它们表明不同组分之间的强相互作用和液态合金中的短序。熔体和锡化钡的热化学性质以及 Ba-Sn 系统中的相平衡用于计算具有理想相关溶液的液态 BaxSn1-x 合金的组分活性、缔合物的摩尔分数以及形成焓和熵（ IAS) 模型。计算中选择了 BaSn 和 Ba2Sn 两个联营公司。Ba-Sn 熔体中组分的计算活性与理想溶液有很大的负偏差，这与它们的热化学性质一致。对于各自的组合物，每种缔合物的最大浓度约为0.65。BamSnn 金属间化合物的计算形成焓是相当高的放热值，与 BaSn3 的公布数据非常吻合，仅与 Ba2Sn 的定性数据吻合。缔合物的生成焓与相应的 BaSn 金属间化合物的生成焓一致，并且 Ba2Sn 的放热略少。这都表明，各个金属间化合物和熔体中不同原子之间的键能彼此接近且相当高。Ba2Sn 缔合体的形成熵较低，而 BaSn 的形成熵量级较高。这表明 BaSn 和 Ba2Sn 缔合体和金属间化合物存在不同程度的有序性。这可能是由于原子振荡频率的不同变化等因素造成的。Ba-Sn 相图的计算液相线曲线与 Sn-Sr 系统的数据一致。