The time-of-flight mass spectrometer was used to determine the thermod
ynamic activities of silver of ternary Ag-Cu-Ge liquid alloys at 1416
K. The ion intensities of silver for 119 different compositions in the
system Ag-Cu-Ge were measured. The mole fractions ranged from 0.105 t
o 1.000 for silver, 0.018 to 0.735 for copper, and 0.048 to 0.690 for
germanium. The activities of copper and germanium in the liquid Ag-Cu-
Ge alloys were calculated by the Gibbs-Duhem integration of activities
of silver. The thermodynamic activities of liquid Ag-Cu-Ge alloys sho
w regular solution behavior at 1416 K.