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This study investigates the fluidity change of Al-Mg binary alloys with the addition of Si and examines the factors that determine flow length in these binary and ternary alloys. Fluidity tests for Al-6Mg-xSi (all compositions in mass percent; x = 0, 3, 5, or 7) alloys were carried out using a spiral-type steel mold. The results show a decrease in both the rate of oxidation and the freezing range, as well as an increase in the heat of fusion of Al-Mg-Si ternary alloys with increasing Si content. Nevertheless, at constant superheating of 60°C, a lower fluidity was achieved in ternary alloys of £ 5 pct Si content than in Al-6Mg alloy. However, further increase to 7 pct Si content yielded a flow length 25 pct higher than for Al-6Mg alloy. Further superheating above the liquidus temperature resulted in increased flow length for Al-Mg-Si ternary alloys, with a flow length increase of about 1 cm per 5°C temperature increase. Instead of solidification range, T aT e range (the temperature difference between the start of the pro-eutectic a-Al phase (T a) and eutectic phases (T e)), was used in this study, as it was found to be a more suitable criterion for predicting flow length for Al-Mg-Si ternary alloys. The key variables for predicting flow length were found to differ based on alloy composition. In the ternary alloys, total heat content and (T aT e) range were found to be the most influential factors driving flow behavior, while the poor fluidity of Al-6Mg binary alloys was found to be driven primarily by high oxidation tendency and low latent heat of fusion.

The objective of this study was to examine the impact of varying magnesium levels in the α-Al + S + T region of the Al-Cu-Mg ternary phase diagram on the solidification process, microstructure development, tensile properties, and precipitation hardening of Al-Cu-Mg-Ti alloys. The outcomes indicate that alloys with 3% and 5% Mg solidified with the formation of binary eutectic α-Al-Al2CuMg (S) phases, whereas in the alloy with 7% Mg, the solidification process ended with the formation of eutectic α-Al-Mg32(Al, Cu)49 (T) phases. Additionally, a significant number of T precipitates were noticed inside the granular α-Al grains in all alloys. In the as-cast condition, the 5% Mg-added alloy showed the best combination of yield strength (153 MPa) and elongation (2.5%). Upon T6 heat treatment, both tensile strength and elongation increased. The 7% Mg-added alloy had the best results, with a yield strength of 193 MPa and an elongation of 3.4%. DSC analysis revealed that the increased tensile strength observed after the aging treatment was associated with the formation of solute clusters and S″/S′ phases.