•Intermetallic particles of Al4Si4Yb/Al10Si4Yb and Al15Cu2Si2Gd phases were identified.•Due to the addition of Zr- and Yb- or Gd in alloys, YS is increased by 50–60 MPa.•Calculation size the ...dispersoids in the investigated alloys should be with of 20–40 nm.•The compression YS significantly increased in the rare earth metals doped alloys.
The microstructure and properties of the Al-5Si-1.3Cu-0.4 Mg-0.15Zr alloys with Yb or Gd additives were investigated. Al4Si4Yb/Al10Si4Yb and Al15Cu2Si2Gd eutectic phases were identified in the investigated alloys. The compression YS at room temperature and 200 °C significantly increased in the rare earth metals doped alloys in the quenched and aged state.
Rare-earth elements improve the mechanical properties of aluminum owing to the formation of the L12-structured nanoprecipitates providing the precipitation strengthening effect. The precipitates ...type, size, and number density depend on the alloy chemical composition and a thermomechanical treatment regime. It is essential to develop the alloys and treatments, providing a combination of the enhanced mechanical strength and a high level of electrical conductivity. This study investigates the influence of thermomechanical treatments on the microstructure, precipitation strengthening, mechanical properties, and electrical conductivity of Al–Er-Yb-Sc alloys with differing Sc content. An as-cast structure of the alloys studied consists of a supersaturated aluminum solid solution and Al3(Er,Yb) phase particles of eutectic origin with the particle thickness of 50–200 nm. A significant strengthening during post-deformation annealing is achieved by precipitation of L12-Al3(Sc,Er,Yb) phase dispersoids of 4–8 nm in size. The mechanical spectroscopy method is successfully used to understand the precipitation kinetics of the studied alloys in comparison with analogous Al-Yb-Y-Sc alloys. This method is highly sensitive to lattice defects parameters, i.e., recrystallization and precipitation kinetics. High-scandium alloys demonstrate an increase of the hardness and tensile strength and insignificant changes in the internal friction background level during post-deformation annealing of cold-worked samples at 300 °C. The yield strength of the Al–Er-Yb-Sc alloys after post-deformation annealing is 142–231 MPa, elongation-to-failure is 3.6–13.5%, and electrical conductivity is 54.8–60.9% IACS, dependent on scandium content and annealing parameters. The studied alloys exhibit high thermal stability of the tensile properties, which remains unchanged during annealing at 300 °C for 100 h.
•Microstructure and properties of Al–Er-Yb-Sc alloys were investigated.•Treatment regime provided a formation of L12 nanoprecipitates are developed.•Rolling stimulates precipitation of L12 dispersoids owing to heterogeneous nucleation.•Internal friction measurements is involved to study precipitation kinetics.•The developed alloys exhibit increased strength and electrical conductivity.
The phase composition, mechanical properties, and superplastic deformation behavior of a novel Al-4.7Cu-1.6Y-0.3Zr alloy were analyzed. The precipitation of Al3(Zr,Y) dispersoids was observed during ...a homogenization treatment. The precipitates have an L12 structure and a mean size of 17 and 19 nm at 540 and 590 °C, respectively. The sheets exhibit a yield strength of 292 MPa, an ultimate tensile strength of 320 MPa, and an elongation of 5.3% after simple thermomechanical treatment and annealing at 100 °C. The Al-4.7Cu-1.6Y-0.3Zr alloy exhibits superplasticity with m > 0.4 and elongation of 300–400% within a temperature range of 550–580 °C and a strain rate range of 1 × 10−4 to 1 × 10−3 s−1.
The effect of impurities on the phase composition and the properties of a new quasibinary Al–Cu–Gd alloy have been investigated. The microstructure in the cast alloy consists of an aluminum solid ...solution, a dispersed eutectic with the Al
8
Cu
4
Gd phase with approximately 1% iron impurity dissolved, and an (AlGdCuSi) phase with an approximate composition of Al
80
Gd
5
Cu
8
Si
5
. High-temperature homogenization at 600°С results in the fragmentation and spheroidization of the solidification-induced phases, including the silicon-containing phase. The annealing of cold-worked sheets at temperatures up to 250°C results in roughly the same softening associated with the recovery and polygonization processes in alloys with and without impurities. The structure is completely recrystallized after 1-hour annealing at 300°C and has an average grain size of 7.5 μm, which slightly increases to 11 μm after annealing at 550°C. The yield strength of the alloys rolled and annealed at 100–150°С is 227–276 MPa with elongation of 5%. Iron and silicon impurities have no negative effects on the microstructure and mechanical properties of this new alloy.
Aluminum-based alloys with advanced processing and service properties are required for the automotive and airspace industries. The current study focuses on the microstructure, recrystallization ...behavior, and elevated- and room-temperatures tensile properties of the novel Al-Cu-Er-Zr-based alloy pretreated using different homogenization annealing regimes. Aluminum solid solution, Al
8
Cu
4
Er phases of crystallization origin, and nanoscale L1
2
-Al
3
(Er,Zr) precipitates were observed in the studied alloy. The alloy exhibited a non-recrystallized structure after annealing of cold-rolled sheets at 300°C, with yield strength of 300 MPa and ultimate tensile strength of 330 MPa at room temperature. The fine-grained structure of the alloy provided superplasticity with elongation to failure up to 450% in the temperature range of 550°C to 605°C and a strain rate range of 10
–3
s
–1
to 10
–2
s
–1
.
The superplasticity and microstructure evolution during superplastic deformation for two Al-Cu-Mg-Zr-Mn-Y and Al-Cu-Mg-Zr-Mn-Er alloys were compared. The heterogeneous microstructure was formed in ...both alloys. Coarse particles of the Cu and Y/Er-bearing and Mn, Fe, Si-bearing phases of solidification origin with a mean size of 1.1/1.4 µm and volume fraction of ~ 9% and fine precipitates of the Mn- and Zr-bearing phases were observed. Precipitates with Zr demonstrated L1
2
structure and contained Cu, Mg, and Y or Er. The residual elements Si and Fe were found in these precipitates for the alloy with Y. Due to PSN effect of coarse particles and Zener pinning effect of fine precipitates, a fine-grained structure with a mean size of ~ 6.5 µm was formed. Distribution of coarse particles in the aluminum solid solution was more homogeneous for Y-bearing alloy, which exhibited more uniform grain structure and a higher grain size stability with much better superplastic properties. The alloy with Y demonstrated strain rate sensitivity of 0.45–0.55 and elongation to failure of 400–550% at 5 × 10
−4
–1 × 10
−2
s
−1
and 575°C. Grain elongation to the tensile direction, dislocation activity in the grain interior and formation of low-angle grain boundaries were observed during superplastic deformation.
The effect of iron and silicon impurities on the phase composition and properties of the Al–4.3Cu–2.2Yb quasi-binary alloy has been determined. In the microstructure of the cast alloy, in addition to ...the aluminum solid solution and dispersed eutectic ((Al) + Al
8
Cu
4
Yb), in which about 1% of iron is dissolved, the Al
3
Yb/(Al,Cu)
17
Yb
2
and Al
80
Yb
5
Cu
6
Si
8
phases are identified, which are not found in an alloy of a similar composition without impurities. After homogenization annealing at a temperature of 590°C for 3 h, the structure is represented by compact fragmented and coagulated intermetallic compounds 1–2 μm in size and a solid solution (Al) with a maximum copper content of 2.1%. The hardness of the deformed sheets significantly decreases after 0.5 h and changes slightly up to 6 h of annealing at temperatures of 150–210°C. After annealing at 180°C for 3 h, a substructure with a subgrain size of 200–400 nm is formed in the alloy structure. The softening after annealing of the rolled sheets at temperatures up to 250°C occurs owing to the recovery and polygonization processes and above 300°C owing to recrystallization. After annealing for 1 h at 300°C, the recrystallized grain size is 7 μm. The grain size increases to 16 µm after annealing for 1 h at 550°C. The Al–4.3Cu–2.2Yb alloy with impurities has a conditional yield strength of 205–273 MPa, a tensile strength of 215–302 MPa, and a relative elongation of 2.3–5.6% in the rolled alloy after annealing. Iron and silicon impurities do not lead to the formation of coarse lamellar intermetallic phases and do not reduce the ductility of the investigated alloy.
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 of the ...cast alloy consists of a dispersed eutectic ((Al) + Al
8
Cu
4
Er), Al
3
Er-phase inclusions located along the dendritic-cell boundaries, and a nonequilibrium AlCu phase. During annealing at 605°C before quenching, the intermetallic phases have high thermal stability: the particle size of Al
8
Cu
4
Er and Al
3
Er phases does not exceed 1–4 µm. The annealing of deformed sheets at temperatures below 300°C leads to a slight decrease in the hardness; grains elongated along the rolling direction are observed in the structure. With an increase in the annealing temperature from 350 to 550°C, the recrystallized grain size increases from 8 ± 1 to 14.5 ± 1.5 μm. The uniaxial tensile tests showed that the annealed alloy possesses sufficiently high strength characteristics: yield stress of 260–280 MPa, ultimate tensile strength of 291–312 MPa, and relative elongation of 5.5–6.1%.
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 Al
3
(Zr,Er), Al
3
(Zr,Y), and Al
20
Cu
2
Mn
3
phases and the Al
8
Cu
4
Y, (Al,Cu)
11
Y
3
, (Al,Cu,Y,Mn), Al
8
Cu
4
ErAl
3
Er, and (Al,Cu,Er,Mn) phases of crystallization origin in new alloys provide high levels of heat resistance.
—
The effect of manganese on the microstructure, phase composition, and mechanical properties of the heat-strengthened deformed Al–5.5Cu–2.0Y–0.3Zr alloy has been studied in this work. The structure ...of the cast alloy was shown to contain a quaternary phase enriched in copper, manganese, and yttrium with a Cu/Mn/Y ratio of 4/2/1, which corresponds to the chemical compound Al
25
Cu
4
Mn
2
Y. The maximum strengthening of the ingot was achieved by aging after quenching at 210°C for 5 h. Three types of precipitates, Al
20
Cu
2
Mn
3
and Al
3
(Zr,Y), were formed in the heat-treated structure in the course of homogenization at 605°C. The size of Al
3
(Zr,Y) particles was 30–50 nm. The Al
20
Cu
2
Mn
3
phase had a longitudinal size of 200–250 nm and a transverse size of 150–200 nm. The disc-shaped precipitates of the θ''(Al
2
Cu) metastable phase with a diameter of 80–200 nm and a thickness of about 5 nm formed upon aging. After rolling and annealing for 1 and 2 h, the hardness was maximum at 150°C. This was explained by a predominance of aging over softening, which retards the growth of dispersoids of Al
20
Cu
2
Mn
3
and Al
3
(Zr,Y) phases and dispersed Al
8
Cu
4
Y and (Al,Cu)
11
Y
3
particles of crystallization origin. At 210°C, the softening of deformed alloy prevails over the effect of aging and as a result, the hardness decreases slightly. The addition of manganese makes it possible to retain a significantly high hardness in the studied alloy at annealing temperatures up to 550°С and to increase the temperature of the onset of recrystallization to 350–400°С. After rolling followed by annealing at 150°C the alloy was shown to possess high mechanical properties: σ
0.2
= 330–334 MPa, σ
u
= 374 MPa, and δ = 3.6–5.5%.
