Moscow Polytechnic University, Moscow, Russia

V. V. Doroshenko, Leading researcher, Dept. of Physics, Candidate of Technical Sciences, e-mail: v.doroshenko@mail.ru
A. A. Aksenov, Chief researcher, Dept. of Physics, Doctor of Technical Sciences, professor, e-mail: a.a.aksenov@mospolytech.ru
D. M. Strekalina, Leading researcher, Dept. of Physics, Candidate of Chemical Sciences, e-mail: d.m.strekalina@mospolytech.ru

University of Science and Technology MISIS, Moscow, Russia
L. E. Gorlov, Laboratory assistant-researcher, Dept. of Metallurgy of Non-Ferrous Metals, e-mail: gorlov@edu.misis.ru

A study was carried out of the influence of calcium on the phase composition (by calculation methods), microstructure, deformability during hot and cold rolling in different modes and mechanical properties (by comparing practical results with calculated ones) of the wrought Al – 3.3 Mg – 2 Ca – 0.7 Mn alloy. It was revealed that the presence of magnesium affects the size of the phase regions, while an increase in its content reduces the crystallization regions (Al). Alloying with calcium helps to reduce the temperatures of phase transformations, as a result of which, in the presence of magnesium, the formation temperature of the eutectic (Al) + Al₄Ca is 35 ^оC lower than in the Al – Ca binary system. The structure of the experimental alloy in the cast state is distinguished mainly by the presence of double eutectic (Al) + Al₄Ca with rare inclusions of the Al6(Mn,Fe) and Al3Mg2 phases. At a quenching temperature of 440 ^оC, two processes occur in the alloy structure: fragmentation of the calcium-containing eutectic and heterogenization of the aluminum solid solution supersaturated with manganese with the formation of rod-shaped inclusions of the Al₆(Mn,Fe) phase. Subsequent holding at a temperature of 550 оC leads to increased fragmentation of crystals of eutectic origin, and the microstructure is distinguished by the presence of a new type of particles corresponding to the ternary compound Al₁₀CaMn₂ located mainly near the particles of the Al₄Ca phase, which is explained by increased diffusion of manganese from (Al) at higher temperatures. After hot rolling, the grain structure of the alloy with calcium is characterized by smaller elongated grains compared to the alloy without calcium. Mechanical tests of sheets after cold rolling and annealing at a temperature of 400 оC for 1 hour showed an increase in the yield strength of at least 25 MPa, which reflects the advantage of calcium alloying. According to the strength calculation, the direct contribution of calcium eutectic to the total strengthening was 9–10 MPa.
The study was carried out at the expense of the Russian Science Foundation grant No. 23-79-00055 and using the scientific equipment of the SRF Research Chemical Analytical Center of the National Research Center Kurchatov Institute.

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