THERMODYNAMICS OF LIQUID NICKEL PALLADIUM ALLOYS BY COMPUTER-AIDED KNUDSEN CELL MASS-SPECTROMETRY

Thermodynamic investigations on liquid binary Ni-Pd alloys have been p erformed by means of computer-aided Knudsen cell mass spectrometry. Th e enlarged ''algebraic intensity ratio'' (AIR) method has been applied for the evaluation of the thermodynamic mixing functions. Two-paramet er thermodynamically adapted power (TAP) series are used for the algeb raic representation of the thermodynamic excess properties. Liquid Ni- Pd alloys are characterized by exothermic molar heats of mixing H(E), slightly negative molar excess entropies S(E) and negative molar exces s Gibbs energies G(E). At 1850 K the minimum H(E) value is -6090 J mol -1 (54.3 at.% Pd), the minimum S(E) value is -0.24 J mol-1 K-1 (59 at. % Pd) and the minimum G(E) value is -5660 J mol-1 (53.7 at.% Pd). At 1 850 K the thermodynamic activities of both components, Pd and Ni, show slight negative deviations from ideality over the entire range of com position.