Moscow Polytechnic University (Moscow Polytech), Moscow, Russia

V. V. Doroshenko, Candidate of Technical Sciences, Senior Researcher of the Department “Materials Science”, Associate Professor of the Project Activity Sector, e-mail: v.doroshenko@mail.ru

A. A. Aksenov, Doctor of Technical Sciences, Professor, Chief Researcher of the Department “Physics”, e-mail: a_aksenov_59@mail.ru

V. V. Eremeeva, Lecturer of the Department “Foreign Language”, e-mail: EremeevaV@bk.ru

National Research Centre “Kurchatov Institute”, Moscow, Russia

R. R. Saifutyarov, Candidate of Chemical Sciences, Senior Researcher, Research Chemical and Analytical Center NRC “Kurchatov Institute” Shared Research Facilities, e-mail: rosya01@gmail.com

This study presents the results of phase composition determination for four alloys in the Al – Mg – Zn – Ca – Cu system. The analysis was performed using both computational (Thermo-Calc) and experimental (DSC, SEM) methods. According to cooling curves based on the Scheil model, the studied alloys exhibit similar liquidus temperatures (613–620 °C) but different solidus temperatures, which decrease with increasing copper content. Conversely, the non-equilibrium solidus temperature increases. These findings align well with DSC results, indicating that solidus temperature shows significant differences only in copper-containing alloys, with higher values by 20–30 °C. The cast microstructure of all alloys is characterized by a degenerate eutectic nature, with an ave rage crystal size up to 4 μm by Feret, and the calculated volume fraction of secondary phases did not exceed 12 vol.%. The aluminum matrix was enriched with magnesium, zinc, and copper, while zinc content remained unchanged with increasing calcium and copper concentrations. As calcium content increased to 1.5%, zinc solubility in the Al₄Ca phase decreased, reaching a minimum at 1.5% Ca and 1% Cu. Copper solubility increased with its content in the alloy; however, after quenching at 440 °C for 3 hours, zinc and copper solubility in the Al₄Ca phase increased. In copper-containing alloys, two additional copper-containing phases were identified after furnace cooling, besides (Al,Zn,Cu)₄Ca and T (AlMgZnCu). At 0.5% Cu, the AlCuMg phase was detected, which was absent at 1% Cu; instead, a ternary compound Al₂₇Ca₃Cu₇ formed, incorporating up to 6 at.% zinc.

The study was carried out using the funds of the Russian Science Foundation grant No. 23-79-01055 (scanning microscopy, differential scanning calorimetry) and the funds of the P.L. Kapitsa grant of the Moscow Polytechnic University, implemented within the Priority 2030 programme (melting and casting, heat treatment).

The structure study was carried out using the scientific equipment of the CKP NRC “Kurchatov Institute - IREA”.

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