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Information × Registration Number 0223U000344, 0122U200144 , R & D reports Title Structure and properties of high-entropy metal diborides made by the method of reaction synthesis popup.stage_title Head Popov Oleksii Yu., Доктор фізико-математичних наук Registration Date 06-01-2023 Organization Taras Shevchenko National University of Kyiv popup.description2 The purpose of the project: reactive hot pressing and research phase composition and structure of polycrystalline multiphase of high-entropy ceramic materials based on diborides of transition metals. The object of the study: the kinetics of densification of multiphase polycarbide powders during heat treatment under pressure and the connection of densification with the formation of new phases of diborides of transition metals. Research methods: X-ray diffractometry, electron and optical microscopy, energy dispersive analysis, analysis of powder body compaction curves, determination of density by hydrostatic weighing. During the implementation of the project, mixtures of TiC, ZrC, HfC, WC, NbC, B4C and Si powders were hot pressed in different ratios and under different conditions (temperature of isothermal holding ranged from 1250 °C to 2000 °C). X-ray phase analysis and electron microscopy were performed research of the obtained materials. The analysis of the conducted studies showed that after heat treatment, samples of ceramic composite materials of the systems: Ti1/3Zr1/3Hf1/3C-Ti1/3Zr1/3Hf1/3В2-С, TiB2-ZrB2-HfB2-NbB2-C, Ti1/3Zr1/3Hf1/3B2-W2B5-SiC-C. It is shown that polymetallic high-entropy diborides of transition metals during reactive hot pressing of the corresponding metal carbides with boron carbide occur in 2 stages: first, at temperatures between 1250 and 1500 °C, monometallic metal diborides are formed, which combine into polymetallic and high-entropy phases at temperatures , higher than 1700 °С. Surplus transition metal carbides in relation to the reaction with boron carbide are also prone to combine into polymetallic carbides that retain the crystalline structure of the corresponding original components. The density of the obtained high-entropy and multiphase samples reached 100% during hot pressing for 8 minutes, which indicates the significant potential of reactive hot pressing for the creation of non-porous high-entropy ceramics.  Product Description popup.authors Kuryliuk Alla M. Ovcharenko Anton О. popup.nrat_date 2023-01-06 Close