The microstructure, hot cracking susceptibility, and mechanical properties of a novel Al–Cu–Y alloy were investigated. The Al–4.7Cu–1.6Y alloy demonstrated very good casting properties, hot cracking susceptibility that is similar to Al–Si–Mg alloys. Analysis of the solidification process showed that the primary Al solidification is followed by the eutectic reaction Liquid→ τ₁(Al₈Cu₄Y)+Al and the peritectic reactions Liquid+ τ₆(Al,Cu)₁₁Y₃)→Al+ τ₁(Al₈Cu₄Y) (612°C) and Liquid+ η(AlCu)→ τ₁(Al₈Cu₄Y)+ θ(Al₂Cu) (595°C). The τ₁(Al₈Cu₄Y) eutectic phase demonstrated high thermal stability during homogenisation treatment. The recrystallisation temperature was in the range 250–350°C after rolling with previous quenching at 540 and 590°C and without heat treatment. The recommended annealing mode for material in the as-rolled condition is 100°C for 1 h: YS = 273 MPa, UTS = 305 MPa and El. = 6.6%.

The microstructure and mechanical properties of the Al–4Cu–2.7Er–0.3Zr alloy were investigated. The precipitates of the L1 ₂ structured phase with sizes 37 ± 12 nm were formed in lines and homogenously distributed inside the aluminium matrix after annealing at 605°C for 1 h. The as-rolled Al–4Cu–2.7Er–0.3Zr alloy developed an increased hardness after 1 h annealing at 100–550°C and 0.5–6 h annealing at 150–250°C due to precipitation of the Al ₃ (Er,Zr) phase. Addition of Zirconium improved the tensile properties relative to those of the Zr-free alloy by approximately 20 MPa: yield strength = 273–296 MPa and ultimate tensile strength = 296–328 MPa in the alloys annealed at 100–150°C. GRAPHICAL ABSTRACT

The microstructure and mechanical properties of new high-temperature casting aluminum alloys Al–5.6Cu–2.0Y–1Mg–0.8Mn–0.3Zr–0.15Ti–0.15Fe–0.15Si and Al–5.4Cu–3.0Er–1.1Mg–0.9Mn–0.3Zr–0.15Ti–0.15Fe–0.15Si are investigated. In an alloy with yttrium, modification with titanium gives rise to a decrease in the grain size from 190 to 40 μm, while the grain size in an alloy with erbium is 25 μm. Regarding the casting properties, the alloys are comparable to silumins alloyed with copper and magnesium. The greatest strengthening effect after quenching is achieved with aging at 210°C; the hardness is 130–133 HV. The tensile yield point at room temperature is 303–306 MPa with a relative elongation of 0.4%. At elevated temperatures of 200 and 250°C, the yield stress decreases to 246–250 and 209–215 MPa, and the elongation increases to 3 and 4–5.5%, respectively. The long-term strength retention after 100 h exposure to 250°C is 117–118 MPa. The presence of a solid solution that is sufficiently alloyed and strengthening dispersoids of the Al₃(Zr,Er), Al₃(Zr,Y), and Al₂₀Cu₂Mn₃ phases and the Al₈Cu₄Y, (Al,Cu)₁₁Y₃, (Al,Cu,Y,Mn), Al₈Cu₄ErAl₃Er, and (Al,Cu,Er,Mn) phases of crystallization origin in new alloys provide high levels of heat resistance.

The evolution of the microstructure and mechanical properties of deformed sheets made of a new Al–4Cu–2.7Er alloy has been studied in the course of homogenization and annealing. The structure...

The microstructure, phase composition, and mechanical properties during heat treatment and rolling of the novel Al-5.0Cu-3.2Er-0.9Mn-0.3Zr alloy were evaluated. A new quaternary (Al,Cu,Mn,Er) phase with possible composition Al₂₅Cu₄Mn₂Er was found in the as-cast alloy. Al₂₀Cu₂Mn₃ and Al₃(Zr,Er) phases were nucleated during homogenization, and θ″(Al₂Cu) precipitates were nucleated during aging. The metastable disc shaped θ″(Al₂Cu) precipitates with a thickness of 5 nm and diameter of 100–200 nm were nucleated mostly on the Al₃(Zr,Er) phase precipitates with a diameter of 35 nm. The hardness Vickers (HV) peak was found after the annealing of a rolled alloy at 150 °C due to strengthening by θ″(A₂Cu) precipitates, which have a larger effect in materials hardness than do the softening processes. The novel Al-Cu-Er-Mn-Zr alloy has a yield strength (YS) of 320–332 MPa, an ultimate tensile strength (UTS) of 360–370 MPa, and an El. of 3.2–4.0% in the annealed alloy after rolling condition.