Аннотация:The work is devoted to the analysis of the nonlinear effects resulting from the influence of excess volumes of intergranular boundaries on the structure of segregations of impurity atoms in polycrystals. It is shown that the adsorption isotherm can describe the nonuniformities in the distribution of impurity atoms in the plane of an intergranular boundary. This suggests the existence of adsorption sites at the internal boundaries of polycrystals. It is proven that an excess volume of intergranular boundaries is the main parameter determining the magnitude of impurity segregations at the boundaries.