Enthalpies of Mixing in Al-Ce-Co Liquid Alloys

The enthalpies of mixing in liquid alloys of the ternary Al-Ce-Co system were determined along four sections (with a constant mole fraction ratio x(Ce)/x(Co)=0.77/0.23 and x(Ce)/x(Co)=0.35/0.65 up to x(Al)=0.2 at 1700 K; with x(Al)/x(Co)=0.76/0.24 up to x(Ce)=0.3 and x(Al)/x(Ce)=0.30/0.70 up to x(Co)=0.23 at 1823 K) via isoperibolic calorimetry. The enthalpies of mixing in the liquid Al-Ce-Co alloys are large exothermic values. A comparison of the experimentally obtained results for the enthalpies of mixing of liquid alloys and those calculated by the regular Redlich-Kister-Muggianu model, taking into account only the data for binary constituent systems, indicates the specific exothermic 'ternary' contribution to the energy of formation of Al-Ce-Co ternary alloys. Data on the partial enthalpy of mixing of cobalt at infinite dilution indicate the involvement of cerium 4 f-electron in the process of alloy formation.