Currently, silumins, which are aluminum alloys, are most widely used in mechanical engineering, construction, and other industries. The use of silumins is often limited due to the presence of large-crystalline structures, such as α-Al dendrites, needle-shaped crystals of eutectic Si, and intermetallic phases. The effect of various additives on and their relationship with the microstructure and mechanical properties of Fe-containing intermetallic phases (Al–Si–Fe and Al–Si–Fe–Mn) has been studied extensively. However, studies of the effect of various additives on the morphology of Fe-containing phases in industrial Al–Si alloys remain relevant.
The effect of small amounts of dysprosium titanate additives (0.01, 0.05, 0.1, 0.5 wt.%) on the morphology and localization of Fe-containing intermetallic phases is studied. Introducing 0.01 wt.% dysprosium titanate causes the transformation of the needle-shaped β-phase to the α-phase in the form of more compact blocks and polyhedral crystals, the size of the α-phase reducing by more than half. The introduction of 0.05, 0.1, and 0.5 wt.% dysprosium titanate does not change the modification of the α- and β-phases and reduces the size of the phases by a factor of 1.5 on average. After the introduction of dysprosium titanate, θ‑Al2Cu particles are dissolved and Cu is concentrated/localized in the Fe-containing intermetallic phases in all the modified alloys.
After the introduction of 0.05–0.5 wt.% dysprosium titanate, the tensile strength of AK12 alloys increases due to a decrease in the size of the α- and β-phases. The modification of the Fe-containing intermetallic phases from the β-phase to the α-phase after the introduction of 0.1 wt.% dysprosium titanate decreases the tensile strength and elongation. The optimum is the addition of tungsten in the amount of 0.1 wt.%, as it leads to the optimal ratio between the structure and the mechanical properties. The tensile strength and elongation increase by 23% on average.
