STRUCTURE AND MECHANICAL PROPERTIES OF THE REFRACTORY MULTICOMPONENT ALLOYS OF THE TA-TI-V-ZR-AL SYSTEM

Refractory high-entropy alloys of the Ta-Ti-V-Zr-Al system, in which the V and Ta contents were varied, were investigated. Criteria, based on the thermodynamic parameters of the binary alloys, melting temperatures of the components, geometric and electronic characteristics of atoms, were used to calculate the possible phase-structural state of the alloys; results were compared with experimental data. Microstructural studies showed the presence of a typical dendritic structure in as-cast alloys with an average grain size of 40 μm, which depends on the concentration of the constituent elements. The microhardness of the alloys was theoretically calculated and experimentally investigated. It was found that the microhardness calculation, based on the data of the valence electrons concentration, bulk modulus and shear modulus, allows to estimate satisfactorily the value of microhardness.