EMF study of liquid Al–Fe–Ge alloys

Abstract

The thermodynamic properties of ternary liquid Al - Fe - Ge alloys have been studied in the temperature range of 1050 - 1250 K by the electromotive force (EMF) technique with a liquid electrolyte. The ternary alloys are character- ized by negative deviations from Raoult's law. dium chloride (purity 99.5 %) and aluminium chloride (pur- ity 99.95 %) were purchased from Sigma-Aldrich and were used for the electrolyte preparation. The electromotive forces of ( - )Ta|Alliq| AlCl3 in KCl + NaCl (azeotropic solution) |(AlxFeyGe 1- x - y)liq| Ta(+) concentration cells were measured in the temperature range of 1050 - 1250 K under argon at atmospheric pressure. The EMF values at one temperature were measured several times both during heating and during cooling of the melt. The thermodynamic properties of liquid ternary alloys were studied for four cross-sections with xGe : xFe being 0.55 : 0.45, 0.6 : 0.4, 0.7 : 0.3, and 0.85 : 0.15. The Al mole fraction was from 0.1 up to 0.8. The cell construction, rou- tine of electrochemical technique, and mathematical pro- cessing of the initial experimental data are described in (4). The partial thermodynamic functions of mixing of Al were calculated from the EMF data for the temperature of 1173 K. The integral excess thermodynamic functions of mixing were defined from the partial ones by integration of the Gibbs-Duhem equation: