The thermodynamic properties of solid cobalt—zinc alloys

Abstract

Reversible potentials of galvanic cells of the form: Pt/(CoZn)(alloy)+ZnO/ZrO 2+CaO/O 2(air)/Pt have been measured at temperatures in the range 873–1173 K. The results have been used to derive the thermodynamic activities and the partial and integral free energies, enthalpies and entropies of formation of the α(f.c.c.) solid solutions and of the β 1, γ, γ 1, γ 2 and δ intermediate phases. Exothermic heats of formation and negative entropies of formation are observed throughout the system. The enthalpies of formation of the f.c.c. solid solutions are compared with those of similar cobalt-based examples and the apparent influence of electronic factors is discussed. An analysis is attempted of the factors contributing to the entropies of formation of the solid phases and their Debye temperatures are estimated.