High temperature thermodynamic properties of solid ta-w alloys

The partial molar and integral molar thermodynamic properties of solid Ta-W alloys have been determined between 1050 and 1300 K using galvanic cells with a thoria-based electrolyte. The activities in this system exhibit negative deviations from ideality, but the magnitude of the negative deviation is less than that observed previously for the Ta-Mo alloys. The negative excess free energies of mixing are due mainly to the enthalpies of mixing. The observed small negative excess entropies of mixing can be attributed to vibrational contributions and/or short range ordering in these alloys. Graduate Student, School of Metallurgy and Materials Science, University of Pennsylvania, Philadelphia, Pa. 19104, School of Metallurgy and Materials Science, University of Pennsylvania.