OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 1 2024 – Mn: 0.018 % – Mg: 0.15 %. The chemical composition of all experimental melts was established experimentally and is presented in Table 1. The ingots were cast into a copper mold with a crystallization rate of 10 °C /s. Ta b l e 1 Chemical composition of the studied alloys Alloy Element weight fraction, % Al Si Fe Mn Mg Zn Zr Sc Er Hf 1590 basic base 0.03 0.06 0.42 5.54 0.19 0.1 0.14 – – 1590 Er0.03-Hf0.05 base 0.04 0.07 0.41 5.54 0.21 0.1 0.14 0.03 0.05 1590 Er0.03-Hf0.1 base 0.04 0.07 0.41 5.58 0.2 0.1 0.14 0.03 0.1 1590 Er0.03-Hf0.16 base 0.05 0.08 0.41 5.58 0.2 0.1 0.14 0.03 0.16 1590 Er0.1-Hf0.05 base 0.04 0.07 0.41 5.57 0.21 0.1 0.14 0.1 0.05 1590 Er0.1-Hf0.1 base 0.05 0.08 0.41 5.53 0.21 0.1 0.14 0.1 0.1 1590 Er0.1-Hf0.16 base 0.05 0.08 0.41 5.57 0.19 0.1 0.14 0.1 0.16 1590 Er0.16-Hf0.05 base 0.04 0.07 0.41 5.55 0.21 0.1 0.14 0.16 0.05 1590 Er0.16-Hf0.1 base 0.05 0.08 0.42 5.56 0.2 0.1 0.14 0.16 0.1 1590 Er0.16-Hf0.16 base 0.05 0.09 0.41 5.58 0.2 0.1 0.14 0.16 0.16 The grain structure of the specimens was analyzed using a complex optical microscope Carl Zeiss Axiovert-40 MAT. The average size of the grains was determined for each specimen using the secant method, which is described in GOST 21073.2. Furthermore, a Tescan Vega 3 scanning electron microscope was used to study the dimensions of intermetallic compounds in its cast state. The exact chemical composition of the structural elements in aluminum alloys 1590 Er0.03-Hf0.05, 1590 Er0.03-Hf0.16, 1590 Er0.16Hf0.05, and 1590 Er0.16-Hf0.16 were determined using energy-dispersive X-ray spectroscopy (EDS). The analysis was carried out using a Max 80T X-detector that operates in the energy range of 0–10 keV and has an energy resolution of 122 eV. The specimen preparation process involved several steps, including mechanical grinding, precision polishing, and electropolishing. Electropolishing was performed under controlled conditions, maintaining a temperature range of 85–110 °C and applying a voltage of 10–30 V. The electrolyte solution used for electropolishing comprised H3PO4 (500 ml), H2SO4 (300 ml), CrO3 (50 g), and H2O (50 ml). Results and discussion The analysis of the microstructure revealed that when cast into a copper chill mold, intermetallic compounds are formed by the process of eutectic reaction, and these compounds contain manganese and iron. The chemical composition of these compounds (as demonstrated in Table 2 and fi gures 1, 2) is similar to Al8 (FeMn), Al12 (FeMn), and MgSi2 [27]. It should be noted that to accurately determine the crystal structure of the phases, X-ray phase analysis is necessary. In this study, EDS analysis is conducted, which can determine the approximate chemical composition of intermetallic compounds and establish its correlation with the previously described phases that have similar compositions [28]. This study has successfully accomplished this. The alloys 1590 Er0.03-Hf0.05, 1590 Er0.03-Hf0.16 and 1590 Er0.16-Hf0.05, which were cast into a copper chill mold, contain manganese and iron and produce intermetallic compounds due to the eutectic
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