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Information × Registration Number 0213U004577, 0113U007248 , R & D reports Title Thermodynamic theory of slippage on grain boundaries in problem of nanostructured metals superplasticity popup.stage_title Head Lyashenko Iakov, Registration Date 18-12-2013 Organization Sumy State University popup.description2 The system of the kinetic equations in the framework of the methods of non-equilibrium evolutionary thermodynamics has been written to describe the superplasticity phenomena. The strengthening-disordering curve, the form of which corresponds to the experimental data, has been obtained using this system. The model has been built using the order parameter, that has the meaning the excess volume, to describe the state of grain boundary (GB). The periodical stick-slip mode of GB melting/solidification has been described. It has been found, that the increasing velocity leads to the increase of the phase transitions frequency. The greater increase of shear velocity leads to reduction of transition frequency due to the appearance of long kinetic areas on the dependencies of the friction force on time. The mechanical analogue of the simple tribological system has been investigated. It has been established that the GB melting occurs when the critical values are exceeded by shear stresses or temperature. The influence of strain defect of GB shift modulus on the phase diagrams of superplasticity modes has been analyzed. It has been shown that it is possible to select such conditions, under which the areas of dry and stick-slip modes of the friction between grains are absent. The dependencies of stationary stresses on the grain temperature have been built. The dependencies of effective potential and probabilities distribution on stresses, appearing in GB, have been constructed. The spatial inhomogeneous through the GB thickness has been considered. The spatial dependencies of stresses, strain and temperature have been constructed. The cases, when the upper and lower grains are moving with equal, but the oppositely directed velocities, and when the lower grain is fixed and the upper is sliding over it, have been considered. Product Description popup.authors Борисюк Вадим Миколайович Жмака Катерина Сергіївна Заскока Антон Миколайович Манько Наталія Миколаївна Метлов Леонід Семенович Хоменко Олексій Віталійович popup.nrat_date 2020-04-02 Close