Аннотация:Features of the microscopic theory of impurity segregations at the intergranular boundaries of polycrystalline substitutional alloys are considered taking into account deformation interactions in the subsystems of planar and point defects of the crystal structure. The integral equation describing the spatial segregation structure is obtained in the mean-field approximation. Theoretical results are used to analyze the segregation structure at the planar special tilt boundaries of binary alloys. The paper shows that the segregation structure is entirely determined by the features of the excess volume distribution in the boundary plane and by the macroscopic alloy parameters that could be measured experimentally.