THERMODYNAMIC PROPERTIES OF TERNARY LIQUID CU-MG-NI ALLOYS

Magnesium vapor pressures were determined over ternary Cu-Mg-Ni alloys along three isopleths with x(Cu)/x(Ni) = 2.0, 1.0, and 0.5 using an i sopiestic method. Data points were obtained between approximately 20 a nd 90 at. pct magnesium in the temperature interval from 1050 to 1350 K. Partial thermodynamic properties of magnesium were derived for the liquid phase, and integral Gibbs energies of formation were computed b y a Gibbs-Duhem integration. The composition dependence of the activit ies at 1173 K is shown for the three sections investigated. The experi mental integral Gibbs energies of mixing for liquid alloys are compare d with the values calculated from binary data by a geometrical formali sm.