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Information × Registration Number 0225U001470, (0122U001556) , R & D reports Title High-temperature composite ceramic materials reinforced with high-entropy alloys based on transition metal borides popup.stage_title Високотемпературні композиційні керамічні матеріали армовані високоентропійними сплавами на основі боридів перехідних металів Head Bohomol Yurii I., Доктор технічних наук Registration Date 01-02-2025 Organization National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute» popup.description1 The aim of the work is to develop of physicochemical bases for obtaining of ceramic composite materials based on boron and silicon carbides reinforced with high-entropy alloys based on transition metal borides with high mechanical properties and operating temperatures (up to 2000 ° C and above). popup.description2  In the research work, the regularities of the structure formation of eutectic alloys based on boron and silicon carbides directionally crystallized, under crucible-free zone melting conditions of unsintered powder compacts, with high-entropy transition metal diborides were studied. It was established that the microstructure of the obtained composites in the entire range of growth rates (1 - 4 mm/min) represents a matrix of boron carbide or silicon carbide, uniformly directionally reinforced in the direction of crystal growth with high-entropy boride based on mixtures of the corresponding transition metal diborides. The influence of the kinetic parameters of crucible-free zone melting on the magnitude of residual macro- and microstresses in the material was investigated using computer modeling and X-ray structural analysis. The micro- and macromechanical characteristics of the obtained directionally reinforced composites were experimentally established. The main strengthening mechanisms were analyzed in a wide temperature range from room temperature to 1600 °C. It was found that at temperatures close to room temperature, the main contribution is made by strengthening mechanisms associated with the presence of residual internal stresses in ceramic composites, which increase due to the difference in the coefficients of thermal expansion of the matrix materials and the reinforcing phase. At high temperatures, the main contribution is made by strengthening mechanisms associated with the plasticity of the phase components. Analysis of the mechanisms of the emergence of covalent components of interatomic bonds in high-entropy transition metal diborides showed that for refractory d-transition metals, strong interatomic bonds are a consequence of the emergence of covalent components during overlapping localized d-orbitals along them. Product Description popup.authors Zaulychnyi Yaroslav V. Kovalenko Mykyta V. Ponomarchuk Serhii H. Solodka Tetiana V Stepanov Oleh V Upatov Mykyta I. Sheremet Vitalii I. Shcherbatiuk Artem O. popup.nrat_date 2025-02-01 Close