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The paper discusses the complex effect of melt overheating with subsequent fast cooling down to the pouring temperature on the crystallization process, microstructure and mechanical properties of Al-Mg-Si aluminum alloy. The results obtained facilitated the establishment of rational modes of melt overheating, leading to a significant change in the dispersion and morphology of structural components. In particular, with an increase in the melt overheating temperature to 900 °C with holding and subsequent rapid cooling to the casting temperature, a decrease in the average size of dendritic cells of the aluminum solid solution from 39 μm to 13 μm was observed. We also noticed the refinement of eutectic inclusions of the Mg2Si phase with compact morphology. An increased level of mechanical properties was noted; the maximum values of tensile strength and elongation reached 228 MPa and 5.24%, respectively, which exceeded the initial values by 22.5% and 52.3%, correspondingly. The microhardness of the aluminum solid solution sequentially increased from 38.21 to 56.5 HV with an increase in the temperature during melt overheating. According to the EDS linear scanning, an increase in the superheat temperature of the melt is accompanied by an increase in the degree of saturation of the solid solution with magnesium.

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When low silicon iron solidifies in the presence of nanosecond electromagnetic pulses, the influ ence of the irradiation time on the process is considered, as well as its influence on the structure and proper ties (hardness, density, local microhardness, corrosion resistance, and wear resistance) of the gray iron that forms. Extending the irradiation time increases the initial temperature of austenite solidification and reduces the eutectic and eutectoidal transformation temperatures. The dependences of the iron's physicomechanical properties on the irradiation time include maxima or minima in the range 10-15 min. For example, the ther mal conductivity doubles in that range.

An assessment of the grain refining effect of nanosecond electromagnetic pulses on the structure of cast aluminum alloys of the Al-Mg-Si system is carried out. The relationship between the amplitude of nanosecond electromagnetic pulses (5, 10, 15 kV) and the structural and morphological parameters of the irradiated aluminum alloys is shown. It was found that the processing of the melts at an amplitude of 15 kV is accompanied by the greatest refinement of the structural components of the alloy, and also by a change in their morphology and a decrease in microporosity in the structure of cast ingot. Theoretical analysis of the influence of nanosecond electromagnetic pulses on the structure and properties of aluminum alloys from the standpoint of the theory of the microheterogeneous structure of metal melts is given.

The current study focusses on the phase composition, solidification path, and microstructure evaluation of gravity cast Al-4Mg-0.5Si-xLa aluminum alloy, where x = 0, 0.1, 0.25, 0.5, 0.75, and 1 wt.% La. A computational CalPhaD approach implemented in Thermo-Calc software and scanning electron microscopy technique equipped with electron microprobe analysis (EMPA) was employed to assess its above-mentioned characteristics. The thermodynamic analysis showed that the equilibrium solidification path of La-containing Al-Mg-Si alloys consists of only binary phases LaSi2 and Mg2Si precipitation along with α-Al from the liquid and further solid-state transformation of this mixture into α-Al + Al11La3 + Mg2Si + Al3Mg2 composition. Scheil–Gulliver simulation showed a similar solidification pathway but was accompanied by an increase in the solidification range (from ~55 °C to 210 °C). Furthermore, microstructural observations were congruent with the calculated fraction of phases at 560 °C and related to α-Al + LaSi2 + Mg2Si three-phase region in terms of formation of La-rich phase having both eliminating effect on the eutectic Mg2Si phase. Quantitative EMPA analysis and elemental mapping revealed that the La-rich phase included Al, La, and Si and may be described as Al2LaSi2 phase. This phase shows a visible modifying effect on the eutectic Mg2Si phase, likely due to absorbing on the liquid/solid interface.