The structure of the new ternary eutectic Al-Ca-Cu system considered as a replacement for the ternary eutectic system Al-Ce-Cu widely used for additive manufacturing has been studied using experimental techniques. The liquidus projection of the Al-Ca-Cu system in the aluminum corner has been suggested based on experiential studies of the microstructure and phase composition of model alloys. The suggested structure of the diagram has two quasi-binary sections: (Al)-Al₂₇Ca₃Cu₇ and (Al)-Al₈CaCu₄ and three invariant eutectic transformations: L→(Al) + (Al,Cu)₄Ca + Al₂₇Ca₃Cu₇ (at 5.6 wt.% Ca, 4.5 wt.% Cu, 595 °C), L→(Al) + Al₂₇Ca₃Cu₇ + Al₈CaCu₄ (at 2.2 wt.% Ca, 13.5 wt.% Cu, 594 °C) and L→(Al) + Al₈CaCu₄ + Al₂Cu (at 0.5 wt.% Ca, 34 wt.% Cu, 544 °C). The limit solubility of copper in aluminum solid solution (Al) at 530 °C reaches ~5.1 wt.% in the ternary phase field (Al) + Al₈CaCu₄ + Al₂Cu and drops to ~2.4 wt.% in the (Al) + Al₈CaCu₄ + Al₂₇Ca₃Cu₇ ternary phase field. For the example of the model ternary hypoeutectic alloys with a predominant content of the eutectic (Al,Cu)₄Ca phase, it has been shown that the system is promising for designing new eutectic-type alloys with a natural composite structure.

In this study, ceramic coatings were grown on the surface of as-cast aluminum alloys via plasma electrolytic oxidation (PEO). The effect of the Si- and Ca-alloying elements in aluminum on the growth process, morphology, composition, mechanical, and corrosion properties of the PEO coatings was investigated. Uniform coatings with a minimum number of defects were formed on the surfaces of Al–Ca alloys. Increasing the Si content in Al led to an increase in the bulk and surface porosity of the coatings. The α-Al₂O₃ phase mainly formed in the coatings synthesized on pure Al and Al–Ca alloys, while an increased amount of Si in Al alloys hindered the formation of the α-Al₂O₃ phase. The coatings had a microhardness of 660–1180 HV_, which was 20–30 times higher than that of the original as-cast alloy. Moreover, the coating on the Al–Ca alloys had the highest peak hardness, which was probably caused by the formation of a greater amount of the α-Al₂O₃ phase. Electrochemical studies in 3.5% NaCl have shown that PEO coatings reduce the corrosion current density. Of all PEO-treated alloys, Al and Al1Ca have the lowest corrosion current density and hence the highest corrosion resistance due to the composition and uniformity of the coating.

This work was focused on studying the possibility of increasing the strength of non-heat-treatable sheet alloy Al2Cu1.5Mn (wt.%) by the joint addition of 1% Mg and 1% Zn. The effect of these elements on the structure and mechanical properties of the new sheet Al2Cu1.5Mn alloy designed for Al₂₀Cu₂Mn₃ dispersoids has been studied by calculations and experimental methods. The obtained data on the phase composition, microstructure, and physical and mechanical properties of the new alloy for different processing routes (including hot rolling, cold rolling, and annealing) have been compared with those for the ternary Mg- and Zn-free alloy. It has been shown that the formation of nanosized Al₂₀Cu₂Mn₃ dispersoids (~7 vol.%) provides for the preservation of the non-recrystallized grain structure after annealing at up to 400 °C (3 h), while Mg and Zn have a positive effect on the strength due to the formation of alloyed aluminum solid solution. As a result, cold-rolled sheets of the Al2Cu1.5Mn1Mg1Zn model alloy showed a substantially higher strength performance after annealing at 400 °C in comparison with the ternary reference alloy. In particular, the UTS is ~360 vs. ~300 MPa, and the YS is 280 vs. 230 MPa. For the example of the Al2Cu1.5Mn1Mg1Zn model alloy, it has been shown that the system is promising for designing new heat-resistant alloys as a sustainable alternative to the 2xxx alloys. The new alloy has an advantage over the commercial alloys (particularly, 2219, 2024, 2014), not only in manufacturability but also in thermal stability. The sheet production cycle for the model alloy is much shorter because the stages of homogenization, solution treatment, and water quenching are excluded.

The processability of the Al3Ca1Cu1.5Mn alloy in the course of thermodeformation treatment has been studied. Its structure has been analyzed in cast and deformed states. The cast structure is composed of primary Al crystals and ultrafine eutectic colonies formed by (Al) and submicron Al₄Ca intermetallide particles with revealed solubility of copper and manganese in both structural components. An essential reduction in size to 300–500 nm has been revealed in the process of deformation for eutectic intermetallides which are uniformly distributed over the composite material volume. Rolled sheets demonstrate a high stability of their properties in the course of thermal treatment at 250 and 350°C. In particular, it has been found that the annealing of a hot-rolled sheet of 0.5 mm in thickness at 250°C for 12 h decreases the alloy microhardness by only ~5%. The most advantageous regimes of the production of rolled sheets provide the balanced mechanical properties, when the ultimate strength is 220–230 MPa, and the ultimate yield strength is 190–200 MPa at a relatively high elongation of 9%.