溶融アルミニウム-錫およびアルミニウム-ガリウム合金の熱力学的研究

抄録

Using the same method as in a previous study for molten aluminum-indium alloys, the measurement of emf of the cells
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\ oindentfor molten aluminum-tin and aluminum-gallium alloys has been carried out. In the molten Al-Sn system, the activities obtained show considerable positive deviations from Raoult’s law and agree well with those estimated from the liquidus line. On the other hand, the activities derived for the molten Al-Ga system obey Raoult’s law fairly well. The activity coefficients determined at infinite dilution are 4.05 for aluminum and 7.11 for tin in the aluminum-tin system at 800°C, and those in the aluminum-gallium system at 700°C are 1.15 and 1.27 for aluminum and gallium, respectively. Other thermodynamic properties of both molten systems have then been derived from experimental data and the heats of mixing obtained are in good agreement with those determined directly with calorimeter by Wittig. The experimental results obtained agree fairly well with the values calculated with models based upon statistical thermodynamics in both aluminum-tin and aluminum-gallium systems. Furthermore, the interaction energy and the short-range order in both systems have been evaluated by the aid of the theory of quasichemical approach, and the results obtained show reasonable agreement with those derived by the classical thermodynamic method.