Kazan Federal University (Naberezhnye Chelny Institute (branch)), Naberezhnye Chelny, Russia

N. N. Safronov, Dr. Eng., Prof., Dept. of Mechanical Engineering, e-mail: safronov-45@mail.ru
G. N. Gorbunov, Postgraduate Student

The effect of silicon alloying of intermetallic alloys of the Fe-Al system in the concentration range of aluminum content of 25–34 % (at.) on the phase composition and hardness is considered. A method for forming cast samples to study these parameters based on the process of self-propagating high-temperature synthesis (SHS) is proposed. The starting materials were red iron oxide, aluminum powder of the PAP-1 grade, welding wires made of aluminum (SvA99) and aluminum alloys (SvAK5, SvAK10). From these materials, precursors were made in the form of aluminum wires with exothermic coating and a seed (a mixture of berthollet salt and aluminum powder) to initiate the SHS process, which was carried out in graphite equipment. Each version of the synthesis of the cast intermetallic sample was performed using five parallel precursors. The obtained experimental data were subjected to statistical processing in order to establish their representativeness and adequacy based on the use of the Smirnov-Grubbs and Student criteria. It has been established that when SvA99 welding wire is used as a precursor, the phase composition of the synthesized intermetallic alloy is represented by the α-phase and FeAl and Fe₃Al intermetallic compounds. The dominant share of aluminum present in the alloy (70%) is used for formation of the FeAl intermetallic compound. The remaining share is distributed mainly to the formation of the Fe3Al intermetallic compound (28 %) and a solid solution in α-Fe (2 %). The introduction of welding wires SvAK5 and SvAK10 into the precursor composition contributed to the alloying of the phase components of the intermetallic alloy with silicon and the disappearance of the α-Fe (Al) solid solution. In this case, the ratio of the remaining phases (FeAl and Fe3Al) changed towards its decrease in the following sequence: 2.46; 1.92; 1.51 with a corresponding change in the grades of aluminum wire in the precursors SvA99, SvAK5 and SvAK10. At the same time, the hardness of the samples has a significant tendency to increase: 44, 52, 56.4 HRC.

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