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Evaluation of A Statistical Thermodynamic Method for Calculating the Composition Dependence of Chemical Potentials in Nonstoichiometric Zirconium Carbide
Author(s) -
DEPOORTER GERALD L.
Publication year - 1969
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1969.tb11932.x
Subject(s) - zirconium , zirconium carbide , carbide , chemical composition , materials science , thermodynamics , carbon fibers , partition coefficient , composition (language) , chemistry , metallurgy , physics , linguistics , composite number , composite material , chromatography , philosophy
Mathematical expressions for carbon and zirconium activities in zirconium carbide are derived from a statistical thermodynamic model, on the assumption that nonstoichiometry is due to vacancies in the carbon sublattice while the zirconium sublattice remains filled. The energy term in the partition function is obtained by using a first‐ and second‐neighbor quasi‐chemical model. Values for the parameters used in the model are determined from available data as a function of composition. For C/Zr atom ratios between 0.59 and 0.85 the energy parameters are approximately composition‐independent, whereas in the composition range 0.85 to 0.99 they are strongly composition‐dependent. The vibrational partition functions of C and Zr in zirconium carbide are estimated and are shown to influence the value obtained for the model parameters.