The high-strength Al–Zn–Mg–Cu alloy with the addition of about 2.9wt.% Ni and 0.3wt.% Zr exhibits superplasticity in the temperature ranged from 380 to 480°C at constant strain rates from 2×10−3 to ...1×10−1s−1 with 400–800% of elongation. Results demonstrate the occurrence of high strain rate superplasticity of the high-strength alloy due to the partially recrystallised grain structure before superplastic deformation and approximately 2μm in size grains formed during superplastic deformation due to the dynamic recrystallisation and PSN. Display omitted
•The alloy exhibits superplasticity at constant strain rates from 0.002 to 0.1s-1.Both coarse Al3Ni and fine Al3Zr particles provide high strain rate superplasticity.•Dynamic polygonisation and recrystallisation are identified during deformation.•Ultrafine grains with 1.8mm in size are formed after 400% of deformation.
The structure, mechanical properties and superplastic behaviour of a high-strength Al–(3.5–4.5)Zn–(3.5–4.5)Mg–(0.7–0.9)Cu–(1.0–3.0)Ni–(0.25–0.30)Zr (wt.%) alloy are investigated. A 570MPa YS and a 610MPa UTS are achieved after T6 heat treatment. The alloy exhibits superplasticity in the temperature ranged from 380 to 480°C at constant strain rates from 2×10−3 to 1×10−1s−1 with a strain rate sensitivity index greater than 0.5 and an elongation of 400–800% due to the stable ultrafine structure with 1.8μm grain size. An EBSD study of the deformation behaviour demonstrated substantial grain refinement resulting from dynamic recrystallisation. High strain rate superplasticity is available due to zirconium addition that provides Zener pinning of grain boundaries, and nickel addition that forms Al3Ni eutectic particles which improved superplasticity due to grain refinement by particle stimulated nucleation.
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•Er addition was found significant grain refinement from 290μm to 90μm.•Al3Er and not identify by XRD ternary (Al,Mg,Er) phases were formed.•High hardening effect in 30HV was obtained ...after annealing at 370°C for 4–10h.•YS=370MPa, UTS=470MPa at El.=9.5% were in the annealed after rolling state.
Microstructure and mechanical properties of a novel Al-Mg-Mn-Zr-Sc-Er alloy with low Sc concentration were investigated. Significant grain refinements and the formation of Al3Er and ternary (Al,Mg,Er) phases were found by scanning electron microscopy and an X-ray analysis with Er addition. A high hardening effect in 30HV was obtained after annealing at 370°C for 4–10h. The maximum level of mechanical properties was found after rolling with a greater part of cold deformation. The research showed that YS=480MPa, UTS=524MPa at El.=4.2% after rolling, and YS=370MPa, UTS=470MPa at El.=9.5% after subsequent annealing at 200°C for 1h.
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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%.
•Ternary (Al,Mg,Y) phase was formed in the as cast alloy, average grain size was 45 ± 5 μm.•Al-4.5Mg-0.5Mn-0.05Sc-0.15Zr-0.2Y alloy has the YS = 422 MPa, UTS = 447 MPa and El. = 5.4% in the deformed ...condition.•YS = 365 MPa, UTS = 423 MPa at El. = 8.3% were in the annealed after rolling state.•After corrosion test the YS and El. decreased on 9 MPa and 2.6% respectively.
The grain size of the Al-Mg-Mn-Zr-Sc-Y alloy was 45 μm. Al3Mg2, Al3Y and ternary AlMgY phases were formed in the as cast condition. High hardening effect in 64HV was obtained after rolling. The optimal combination of strength and plasticity was achieved after annealing at 150 °C: YS = 365 MPa, UTS = 423 MPa and El. = 8.3%.
Superplastic behaviour of binary two-phase brass and brasses with aluminium addition are compared. Indicators of the superplasticity are considered at a temperature range of 525–600°C and at constant ...strain rates of 5·10−4s−1 and 1·10−3s−1. The effect of aluminium addition on the superplastic deformation indicators is studied. Improvement of superplasticity and significant decreasing of cavitation are identified due to alloying by aluminium. Surface relief of the samples after superplastic deformation, and grain boundary sliding contribution are analysed, and deformation mechanisms are discussed.
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 structure and properties of rolled Al–Zn–Mg–Cu–Zr–Y(Er) alloys doped with manganese and modified with titanium have been studied. According to the results of tensile testing in the deformed state ...after annealings at 120–150°C for 1 h, the AlZnMgCuMnTi and AlZnMgCuMnTiEr alloys show a high yield strength of 417–456 MPa with a small relative elongation of 2–5.2%. The presence of additional dispersion-forming elements, such as yttrium and erbium, increases the density of particles precipitated in the course of homogenization annealing due to increase in the recrystallization onset temperature and in the hardness of the rolled alloys. After 1 h annealing at 350°C, the AlZnMgCuMnTi alloy has a completely recrystallized structure, while the alloys doped with yttrium and erbium only start to recrystallize. After quenching from the heated state at 465°C and aging at 120°C, the test alloys have a yield strength of more than 410 MPa, a tensile strength of more than 520 MPa, and an elongation of more than 10%. The obtained parameters are higher than the parameters of clad sheets of the high-strength heat-hardened Al–Zn–Mg–Cu (B95A) alloy and rods of the AlZn
4.5
Mg
1.5
Mn and AlZnMg
1.5
Mn alloys, and are comparable to the characteristic levels of rods of the Al–Zn–Mg–Cu (B95) alloy.
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 microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity were investigated. Eutectic Al3Y-phase particles of size 100–200 nm were ...detected in the as-cast microstructure of the alloys. Al3Y-phase particles provided a higher hardness to as cast alloys than homogenized alloys in the temperature range of 370–440 °C. L12 precipitates of the Al3(ScxYy) phase were nucleated homogenously within the aluminium matrix and heterogeneously on the dislocations during annealing at 400 °C. The average size of the L12 precipitates was 11±2 nm after annealing for 1 h, and 25–30 nm after annealing for 5 h, which led to a decrease in the hardness of the Al-0.2Y-0.2Sc alloy to 15 HV. The recrystallization temperature exceeded 350 °C and 450 °C for the Al-0.2Y-0.05Sc and Al-0.2Y-0.2Sc alloys, respectively. The investigated alloys demonstrated good thermal stability of the hardness and tensile properties after annealing the rolled alloys at 200 and 300 °C, due to fixing of the dislocations and grain boundaries by L12 precipitates and eutectic Al3Y-phase particles. The good combination of strength, plasticity, and electrical conductivity of the investigated Al-0.2Y-0.2Sc alloys make it a promising candidate for electrical conductors. The alloys exhibited a yield stress of 177–183 MPa, ultimate tensile stress of 199–202 MPa, elongation of 15.2–15.8%, and electrical conductivity of 60.8%–61.5% IACS.
