Исследование физико-механических свойств горячепрессованных композиционных керамик системы Hf–Ti–Cr–Fe–V–N

Abstract

The concept of synthesizing multicomponent (five or more components) systems in equiatomic or near-equiatomic percentages has opened a new class of materials, including high-entropy alloys (HEAs) and high-entropy ceramics (HEC). The composition of each element varies from 5 to 35 at.%. It is generally accepted that the exceptional performance of high-entropy materials is achieved through four “basic effects”: the highentropy effect, the lattice distortion effect, the slow diffusion effect, and the “cocktail” effect. The properties of multicomponent systems are determined not only by the constituent elements, but also by the formation of phases. Thus, depending on the composition and methods of preparation and processing of the alloy, the ordered and disordered phases of the solid solution are formed in the HEAs. Both the atoms of individual elements and the resulting phases contribute to the properties of HEAs. They possess valuable properties such as high corrosion resistance, wear resistance, hardness, and other particular mechanical properties. This class of materials is under active scientific study, and the methods for their production, such as vacuum arc melting, selective laser melting, magnetron sputtering, are being developed. One of the promising and highly efficient methods for producing HEAs and HECs is self-propagating high-temperature synthesis (SHS). The main advantages of this method are high productivity, low energy consumption, environmental safety, regulation of the structure and properties of the final products, and synthesis mode control due to the possibility of selecting various combustion temperature and pressure values. This study examines the effect of the temperature regime of the hot-pressing process on the structure and properties of ceramic samples of the Hf-Ti-Cr-Fe-V-N system. HEC materials are obtained as a result of high-temperature exothermic reactions with preliminary mechanical activation of the powder mixture in a planetary mill. The preparation of compact ceramic samples is carried out using the hot-pressing method in the temperature range of 1300–1450 °C. The X-ray diffraction analysis of the resulting samples allows one to determine the dependence of the structure, density, and hardness on the pressing temperature. The maximum hardness (1858±50 HV) is obtained at a pressing temperature of 1450 °C.