A Contribution to the Calculation of the Concentration of Vacancies and Complexes

A thermodynamic method is proposed to calculate the equilibrium concentration of both, free and bound vacancies. The formula for the entropy of mixing avoids the dependence of the sequence concerning the distribution of objects in the lattice. The lattice sites are occupied by particles of different qualities considering not only atoms and free vacancies but also complexes, requiring two or three lattice sites. The model is applied to both, pure f.c.c. metals and binary and ternary alloys. Expressions for the equilibrium concentrations are derived. The results are compared with those of other authors. Some implications and limitations of the model are discussed.