OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 We have proven the effectiveness of the described approach by investigations of FTi35S5 ferrotitanium, which consists of 82 % of (Fe,Al)2Ti intermetallic compound, and P-803 carbon black powder mixtures. It is shown that in mechanically activated ferrotitanium and carbon black powder mixtures, a reaction occurs both in wave and thermal explosion modes with the formation of a composite based on 50 vol. % of titanium carbide. The synthesis reaction occurs in solid-phase mode at the combustion temperatures of 900–950 °C. Due to the low combustion temperatures, coarsening of the structure does not occur and the carbide particles have a submicron size. Since FTi35S5 industrial ferrotitanium contains many impurities, i.e. silicon, aluminum, the purpose of the study is to investigate the reaction products in mechanically activated mixtures of iron titanides – Fe2Ti and FeTi – with carbon (carbon black) and to examine the possibility of synthesizing iron-matrix composites strengthened with submicron titanium carbide particles. Materials and research methodology The intermetallic powders were obtained by vacuum sintering of compacts at a temperature of 1.250 °C with isothermal holding for 2 hours from mechanically activated mixtures of elemental powders of two compositions: 2Fe + Ti (77.7 wt. % iron + 22.3 wt. % titanium) and Fe + Ti (63.6 wt. % iron + 36.4 wt. % titanium). Subsequently, the intermetallic powders were used as initial powder materials for the synthesis TiC + Fe binder composites. A detailed procedure for the preparation of these intermetallic powders and the specifications of the initial powders are described in [31]. By sintering the 2Fe + Ti mixture, it was possible to obtain a Fe2Ti single-phase intermetallic compound. According to the results of X-ray diffraction analysis, the sintering product of a compact from the Fe + Ti mixture contained 82 vol. % of Fe2Ti compound and 18 vol. % of target FeTi phase. The reason for the predominant formation of the Fe2Ti compound is twice the negative value of the enthalpy of the Fe2Ti compound formation compared to that for FeTi: -87.45 and -40.58 kcal/mol, respectively [32]. Carbon black was added to intermetallic powders with the above phase composition in the amount necessary to convert all the titanium contained in the intermetallic compounds into titanium carbide. The obtained mixtures were processed in an Activator-2S planetary mill at a rotation speed of 755 rpm (40 g) for 10 minutes with the ethanol additive to exclude the powder sticking to the grinding balls and drum walls. Cylindrical specimens with a diameter of 20 mm were compacted from the mechanically activated mixtures and sintered in a vacuum at a temperature of 1,200 °C with isothermal holding of 60 minutes. The structure and phase composition of sintering compacts were studied using the equipment of the Shared Use Center “Nanotech” of the ISPMS SB RAS by optical metallography (AXIOVERT-200MAT optical microscope, Zeiss, Germany), scanning electron microscopy (EVO 50 scanning electron microscope, Zeiss, Germany) and X-ray diffraction analysis (DRON-8N X-ray diffractometer, Bourevestnik, Russia). Diffraction patterns were obtained in an angle range of 2Ɵ = 35°–125° with a scanning step of 0.1° for exposure of 1 second using CuKα irradiation. Identification of phases was carried out using the ASTM X-ray database. Processing of the primary results was carried out using the MAUD software and “Qualitative and quantitative phase analysis” (Bourevestnik, JSC, St. Petersburg) by Rietveld method using the COD database. Results and discussion Sintered materials According to the results of X-ray diffraction analysis (fig. 1, Table 1), the sintering products of compacts of both compositions contain the target phases (titanium carbide, α-iron) and trace amounts of other phases. Thus, the titanium contained in iron titanides reacts with carbon to form carbide and reduced iron. The titanium and iron carbide relative content in the sintering products depend on the elemental ratio in the reaction mixtures, which kept to be unchanged during the synthesis process. The lattice parameter of titanium carbide is slightly lower than the reference values [33] for equiatomic titanium carbide, i.e. 0.4327 nm, which is the result of a composition shift from equiatomic towards titanium. According to the titaniumcarbon equilibrium diagram [34], titanium carbide has a wide homogeneity region extending from TiC0.5 to
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