OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 3 2023 synthesis in the wave mode only with preliminary heating of the compacts to temperatures over 700 °C. In [16], mixtures corresponding to the compositions of binary intermetallic compounds were subjected to short-term, i.e. up to 10 minute duration, intense MA at subsequent rapid heating, i.e. about 300 K/min. The synthesis reaction in the thermal explosion mode was initiated in the 450–500 °C range depending on MA time and the mixture composition. In [17], the Fe-20 % Ti mixture was processed for 4 and 20 minutes in a planetary mill at intensity close to that used in [16]. The formation of the intermetallic compounds was not detected even when the MA mixture was annealed at 500 °C. A possible reason for the mismatch in the results of [16] and [17] is the different heating rates of the MA mixtures. With rapid heating, the reaction surface is not contaminated by reaction diffusion products at the stage of slow heating to the annealing temperature, and the synthesis reaction occurs in the thermal explosion mode. Thus, the problem of developing technological modes of mechanical activation of powder mixtures and the subsequent synthesis of single-phase intermetallic compounds of the titanium-iron system remains unresolved. The tasks of this study are to investigate the phase composition of the synthesis’ products in mechanically activated powder mixtures of titanium and iron, and to investigate the possibility of obtaining single-phase binary intermetallic compounds. Two compositions were used, corresponding to FeTi and Fe2Ti compounds. The Fe2Ti intermetallic is also of practical interest as a magnetic material [18]. Research methodology The reaction mixtures were prepared from titanium powder with a dispersity of less than 160 μm and iron powder with a dispersity of less than 5 μm. The morphology of the powders is shown in fig. 2. The powders’ weighted portions of 15 grams were mixed for 4 hours in a mixing tank and placed in the jars of an Activator-2S planetary ball mill. To prevent sticking of the powders to the balls and walls, 0.5 cm3 of alcohol was injected into each jar. Mechanical activation was carried out at a jar rotation speed of 755 rpm (centrifugal acceleration 40 g). Aweight ratio of steel grinding balls with a diameter of 6 mm to the reaction mixture was equal to 20. In total, every mixture was mechanically activated for 20 minutes. To prevent the Activator overheating, the jars’ rotation was stopped every 10 minutes, for 10 minutes to cool the jars with water flow. The mechanically activated mixtures were poured into cylindrical titanium containers and slightly compacted. The containers were placed into a sealed reactor. A design of the reactor is presented in [19]. The reactor was lowered in the furnace preheated up to 800 °C. The reactor was continuously purged with argon at a flow rate of 4 L/min. The temperature was registered automatically by two thermocouples. The junction of the first thermocouple, thermally insulated from the furnace radiation with a layer of asbestos, was located on the outer wall of the reactor. The junction of the second thermocouple was located in the a b Fig. 2. SEM images of the initial powders morphology: a – VM iron* (left side of the photo – back scattered electron image (BSE), right one – secondary electron image (SE)); b – TPP-8 titanium** * ТC 6-09-2227-81 «Reduced metallic iron»; ** ТC 1791-449-05785388-99 «Titanium sponge powder»
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