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.

Increasing the strain rate at superplastic forming is a challenging technical and economic task of aluminum forming manufacturing. New aluminum sheets exhibiting high strain rate superplasticity at strain rates above 0.01 s⁻¹ are required. This study describes the microstructure and the superplasticity properties of a new high-strength Al-Zn-Mg-based alloy processed by a simple thermomechanical treatment including hot and cold rolling. The new alloy contains Ni to form Al₃Ni coarse particles and minor additions of Zr (0.19 wt.%) and Sc (0.06 wt.%) to form nanoprecipitates of the L1₂-Al₃ (Sc,Zr) phase. The design of chemical and phase compositions of the alloy provides superplasticity with an elongation of 600–800% in a strain rate range of 0.01 to 0.6/s and residual cavitation less than 2%. A mean elongation-to-failure of 400% is observed at an extremely high constant strain rate of 1 s⁻¹. The strain-induced evolution of the grain and dislocation structures as well as the L1₂ precipitates at superplastic deformation is studied. The dynamic recrystallization at superplastic deformation is confirmed. The superplastic flow behavior of the proposed alloy is modeled via a mathematical Arrhenius-type constitutive model and an artificial neural network model. Both models exhibit good predictability at low and high strain rates of superplastic deformation.

In the present research an Al–7.7%Mn–4.9%Zr–3.2%Cu (wt%) alloy was processed by mechanical alloying (MA) followed by hot press sintering. The microstructure, phase composition, and mechanical properties of the MA granules and sintered samples were investigated. The dissolution of Mn, Zr, and Cu with further precipitation of the Al₆Mn phase were observed during high-energy ball milling. In the alloy processed without stearic acid after milling for ~10 h, an Al-based solid solution with ~4.9 wt%Zr, ~3.2 wt%Cu and a ~5 wt%Mn with a grain size of ~16 nm and a microhardness of ~530 HV were observed. The addition of stearic acid facilitated Mn dissolution and precipitation of the Al₆Mn phase during milling but led to the formation of the ZrH₂ phase that decreased the Zr solute and the microhardness. Precipitation of the Al₆Mn, L1₂–Al₃Zr, and Al₂Cu phases during annealing and sintering of the MA granules in the temperate range of 350–375 °C was observed, and an additional Al₂₀Cu₂Mn₃ phase was precipitated at 400–450 °C. Hot-press sintering at 450 °C provided a low fraction of cavities of ~1.5%, the yield strength of 1100 MPa, ultimate compressive strength of 1200 MPa, strain at fracture of 0.5% at room temperature, the yield strength of 380 MPa, ultimate compressive strength of 440 MPa, and strain at fracture of 3.5% at 350 °C. The microstructural evolution during high-temperature deformation on the sample surface was studied and the differences in deformation behavior for the alloys sintered at different temperatures were discussed.

The current study analyzed the effect of Ni content on the microstructure and superplastic deformation behavior of the Al-Mg-Si-Cu-based alloy doped with small additions of Sc and Zr. The superplasticity was observed in the studied alloys due to a bimodal particle size distribution. The coarse particles of eutectic origin Al₃Ni and Mg₂Si phases with a total volume fraction of 4.0–8.0% and a mean size of 1.4–1.6 µm provided the particles with a stimulated nucleation effect. The L1₂– structured nanoscale dispersoids of Sc- and Zr-bearing phase inhibited recrystallization and grain growth due to a strong Zener pinning effect. The positive effect of Ni on the superplasticity was revealed and confirmed by a high-temperature tensile test in a wide strain rate and temperature limits. In the alloy with 4 wt.% Ni, the elongation-to-failure of 350–520% was observed at 460 °C, in a strain rate range of 2 × 10⁻³–5 × 10⁻² s⁻¹.

Increasing the strength of Al-based alloys is an important issue of physical metallurgy and industrial processing. Severe plastic deformation and related extension of solid solubility during mechanical alloying provide an opportunity for significant strengthening due to grain refinement, solid solution, and precipitation strengthening mechanisms. During mechanical alloying, an anomalous increase in the solid-state solubility of alloying elements occurs. The present study focuses on the investigation of the pre-milling treatment to the microstructure, phase composition, and solubility in Al-7.7 Mn-3.5 Cu (wt%) alloy processed by a high-energy ball milling of Al-14.3 Mn-6.5 Cu (wt%) master alloy diluted with Al powder. During milling, the mean granular size decreased to ~5 µm, and a strong grain refinement occurred. According to our TEM and XRD data, ball milling provided a mean grain size of 13–14 nm and a microhardness of 490–540 HV. The lattice parameter of the Al-based solid solution decreased with an increase in the milling time to 7.5–10 h, which suggested the dissolution of the alloying elements, and the lattice parameter increased at a higher milling time of 12.5–40 h, which suggested the decomposition of the solid solution. The XRD data revealed the dissolution of the Al₆Mn and Al₂₀Cu₂Mn₃ solidification-originated phases with a further precipitation of the Al₆Mn dispersoids. Pre-milling of the master alloy entailed a significant decrease in the minimal lattice parameter value from 0.4029 nm to 0.4023 nm due to an increase in the Mn solute content from 6.2 wt% (3.3 at%) to 7.5 wt % (4.0 at%) in the studied alloy during high-energy ball milling.