Search

The special approach within nonequilibrium evolutional thermodynamics is developed. Considering two-defect approximation, which takes into account the densities of grain boundaries and dislocations, this theory describes the evolution of defect subsystems of polycrystalline materials and the formation of stationary submicrocrystalline or nanocrystalline structures. The influence of additive noise of basic parameters allows to describe more accurately the self-consistent behavior of considered structural defects and to provide the possibility of the existence of new fragmentation modes during severe plastic deformation. The phase diagram is constructed. The conditions of simultaneous existence of two limiting structures that correspond to the regime of the phases formation with different grain sizes are found. The distribution of the realization of grain boundaries density helps to estimate quantitatively the composition of grain structure over the volume of metal sample.