Thermodynamic Studies of the Liquid Aluminum Alloy Systems

Abstract

Thermodynamic properties of the liquid binary aluminum alloys have been investigated by various equilibrium measurements. The measurement of the electromotive force was carried out for the Al–In, Al–Sn, Al–Ga and Al–Au systems using the following cells:
Al (l) |NaCl+KCl, AlCl₃|Al–Me (l)
For a part of the Al–Au system, the distribution of gold between the Pb–Au and Al–Au phases was measured to obtain the activity of gold because the emf method was not suitable at temperatures higher than 1000°C. The liquid Al–Zn and Al–Te systems were investigated by the dew point method which was improved so as to detect the dew point thermoanalytically.
The activities derived from the measured values show considerably positive deviations from Raoult’s law for the Al–In, Al–Sn and Al–Zn systems, while in the Al–Ga system obey Raoult’s law fairly well, and show negative deviations in the Al–Au and Al–Te systems. The activity values thus obtained have compared with the previous data and those estimated theoretically in various ways. Moreover, activity coefficients at infinite dilution have also been calculated.
Other thermodynamic quantities of these systems have been derived from experimental data, and the limits of the miscibility gap in the Al–In system, which have not yet been established, was confirmed by the data on the electromotive force observed.