The Gibbs adsorption isotherm and Wagner’s definition of excess solute at surfaces and grain boundaries were both extended to include other crystalline defects, like dislocations and vacancies. By using a thermodynamic state function which was suitable for a partially open system, open with respect to solvent and closed withrespect to solute atoms, a generalized Gibbs adsorption isotherm could be derived. Thus solute segregation to dislocations and vacancies gave rise to a reduction of their formation energies, too. The results of the presented treatment were compared with results stemming from statistical mechanics or computer simulations. Special attention was paid to the question whether defect energies might become zero or negative.

Reducing Grain Boundary, Dislocation Line and Vacancy Formation Energies by Solute Segregation I - Theoretical Background. R.Kirchheim: Acta Materialia, 2007, 55[15], 5129-38