We develop a procedure for the evaluation of the surface y and interphase 7m energy of deformed solid bodies subjected to atomic irradiation or placed in a liquid metal. The characteristic of the surfaces ~/m appears in the Griffith, Griffith-Orowan, Kamdar-Westwood, and Kontorova-Frenkel fracture mechanics criteria and their modifications for the case of the size strength effect.In estimating the strength of deformable solid bodies (metals and dielectrics) at least one geometric dimension of which lies within the range 1-10 mm, it is necessary to take into account the size effect, i.e., the dependence of the ultimate stress on the geometric sizes of the specimen [ 1,2]. We restrict ourselves to the following two cases of the influence of environments on the bodies:(a) the action of irradiation promoting an increase in the concentration of point defects (vacancies and interstitial atoms) in the surface layer [3,4] and (b) a specimen placed in a liquid metal (e.g., in mercury) [5].On the basis of the analysis of stresses in the surface layers of solid bodies, we propose to determine their surface ~, and interphase ' Ym energy and changes in their values with an aim to use these characteristics for the creation of new strength criteria and evaluation of the parameters appearing in the Kamdar-Westwood criterion and its modifications. Procedure of Evaluation of the Surface EnergyAssume that the domain x > 0 (V1) is occupied by a metal (e.g., copper) and the domain x < 0 (V2) is filled with air (x, y, and z are Cartesian coordinates). The specimens (solid bodies) are irradiated by particles, the integral doze of which is equal to F. We assume that the stresses ~y/parallel to the surface are proportional to the doze F, i.e., ~y~ = CF [3,4], where C is a constant. This enables us to predict the behavior of the stresses Cry in the surface layer.For the surface tension o~ we obtain [6] h O h = fOydx, Oy = Oys + Oyd, Oy = (Yz, and Oya = CF,o where h is the effective thickness of the surface layer. It can be estimated by using the conditionwhere p = 100 kPa is atmospheric pressure. The components of stresses ox and oy are found from the equations of state [7] Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv.