Reducing grain boundary, dislocation line and vacancy formation energies by solute segregation

The extended version of the Gibbs adsorption isotherm including dislocations and vacancies is used to analyse existing experimental data. Thus phenomena and models like solid solution softening, hydrogen-enhanced local plasticity, brittleness of hydrides and superabundant vacancies could be interpreted on the basis of thermodynamics as caused by changing the defect energy by solute segregation; like in Gibbs' original work, surface and grain boundary energies are reduced by excess solute. In addition, the analysis of experimental results addresses the question whether zero or negative defect energies are feasible and how this will affect materials behaviour