Zakarian D. First-principles methods for calculating the physical characteristics of refractory binaryeutectic composites.

For refractory materials was developed the method for calculating the elastic characteristics and theoretical strength for uniaxial deformations. A model is developed for assessing the strength of nanocrystals, depending on their size and shape. It is shown that in order to determine the composition and temperature at the eutectic point, it is sufficient to construct a thermodynamic potential for a system in the solid state, which has a maximum in concentration and a minimum in temperature. From the extreme point of the thermodynamic potential, a system of equations is obtained whose solution determines the composition and melting temperature of the system at the eutectic point. To study the temperature dependence of the physical properties of binary eutectic systems, a "quasi-harmonic approximation" model is constructed on the basis of the pseudopotential method. This model allows inclusion of nonharmonic effects associated with the thermal expansion of materials within the framework of the harmonic approximation. An approach is presented to solve the problem of taking into account the intercomponent interaction, as well as the temperature dependence of the physical characteristics. Taking into account the intercomponent interaction leads to an increase in the permissible degree of deformation of the refractory component, which ultimately contributes to an increase in the ultimate strength of the binary system. Based on the results of the computational experiment, the role of the intercomponent interaction in the formation of eutectic systems was studied.