OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 3 2023 According to the results of X-ray phase analysis (fig. 4, Table 1), after 20 minutes of mixtures processing at the selected intensity, the phase composition of the mixtures remains indentical. That means mechanical synthesis of intermetallic compounds does not take place. In the products of a thermal explosion, a small content of intermetallic compounds is determined (at the sensitivity level of the method). In this case, the Fe2Ti compound is also present in the combustion products of the Fe + Ti composition in an amount approximately equal to the content of the target FeTi compound. The result correletes with the thermal explosion thermographs (fig. 3). Apparently, the formation of Fe2Ti, which has a large negative enthalpy, is the reason for the low observable thermal explosion in a Fe + Ti mixture. a b Fig. 4. X-ray patterns of mechanically activated mixtures (1) and thermal explosion products (2) in Fe + Ti (a) and 2Fe + Ti (b) mixtures Ta b l e 1 Phase composition of the mechanically activated (MA) mixtures and the thermal explosion (TE) products Mixture composition Mixture processing Phase volume content, % Fe (6-696) Ti (5-682) FeTi (19-636) Fe2Ti (15-336) Fe + Ti MA 70.7 29.3 – – Fe + Ti MA + TE 71.4 12.9 6.6 9.1 2Fe + Ti MA 75.1 18.7 – 6.2 2Fe + Ti MA + TE 72.0 23.1 – 4.9 Since synthesis under thermal explosion conditions in MA mixtures gives an insignificant volume of target products, powder mixtures of both compositions (including those without preliminary MA), as well as thermal explosion products, were annealed in vacuum in order to establish technological conditions (temperature and time), providing the maximum yeild of target products. The results of detected phase composition after annealing are shown in Table 2. Due to the superposition of lines of different phases, the quantitative detection of the phase content is complicated. Therefore, the table contains tne approximate indications which obviously show that the Fe2Ti intermetallic compound is the main phase in all cases, regardless of the mixtures composition the and the heat treatment mode. However, we failed to achieve a single-phase state of Fe2Ti in annealed mechanically activated 2Fe + Ti mixtures. After annealing, a
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