Thermodynamics of liquid nickel-palladium alloys by computer-aided knudsen cell mass spectrometry

Abstract

Thermodynamic investigations on liquid binary Ni-Pd alloys have been performed by means of computer-aided Knudsen cell mass spectrometry. The enlarged “algebraic intensity ratio” (AIR) method has been applied for the evaluation of the thermodynamic mixing functions. Two-parameter thermodynamically adapted power (TAP) series are used for the algebraic 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 excess 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 1850 K the thermodynamic activities of both components, Pd and Ni, show slight negative deviations from ideality over the entire range of composition.