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.
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 effect of Zr addition to the novel Al-Er-Y alloy on microstructure, phase composition, recrystallization behavior, mechanical properties and electrical conductivity is studied. Formation of the ...Al3Y, Al3Er and Al3(Er,Y) intermetallic phases in the Al-Er-Y alloy is proved by SEM. Zirconium leads to the formation of the Al3(Er,Y,Zr) eutectic phase. We demonstrate the formation of nanosized Al3(Er,Y) and Al3(Er,Y,Zr) dispersoids in the Al-Er-Y and Al-Er-Y-Zr alloys, respectively. The recrystallization temperature for the Al-Er-Y alloy at about 365 °C is recorded by dynamic mechanical analyzer. Zirconium addition to the Al-Er-Y alloy increases the recrystallization temperature to above 400 °C. The YS and UTS of the Al-Er-Y alloy are decreased after annealing of the rolled sheets from 130 to 115 MPa and from 142 to 125 MPa, respectively. The average tensile properties of the Al-Er-Y-Zr alloy in the deformed and annealed conditions are YS = 144 ± 3 MPa and UTS = 156 ± 3 MPa with 11 ± 1% elongation. The Al-Er-Y alloy demonstrates a good electrical conductivity of 64–64.7% IACS. Zirconium addition decreases electrical conductivity to 57% IACS.
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•Al3Y, Al3Er and Al3(ErY) phases were formed in the AlErY alloy.•The formation of the 5 nm Al3(ErYZr) dispersoids in the AlErYZr alloy was showed.•Zr increased the recrystallization temperature of the AlErY alloy higher than 400 °C.•The YS = 144 MPa and UTS = 156 MPa with El. = 11% were found for the AlErYZr alloy.•The AlErY alloy demonstrated a good electrical conductivity in 64–64.7% IACS.
The microstructure and properties of the novel heat resistant Al–3Ce–7Cu alloy produced by selective laser melting were investigated. Fine Al
11
Ce
3
and Al
6.5
CeCu
6.5
eutectic phases were found in ...the microstructure. Annealing at temperatures in the 250–400 °C range leads to a decrease in the hardness. Hardness has larger values after annealing at 350 and 400 °C than at 250 °C due to the precipitation of nanosized particles. The low hardness after quenching and aging at 190 °C is caused by quench stress relief and the absence of aging hardening because of poor solid solution. The as-printed yield strength, ultimate tensile strength and elongation are 274 MPa, 456 MPa and 4.4%, respectively. High mechanical properties of the Al–3Ce–7Cu alloy were demonstrated by high temperature tension and compression tests.
The superplastic deformation behaviour at elevated temperatures and constant strain rates of two fine-grained AA5083 type aluminium alloys was investigated. The first alloy with chromium contains ...Al6(Mn,Cr) particles and the second alloy without chromium has Al6Mn particles. The effective activation energy of superplastic deformation and the activation parameters for the grain boundary relaxation was calculated. The microstructure evolution and contributions of grain boundary sliding, intragranular deformation and diffusion creep to total superplastic deformation were studied by SEM, EBSD, FIB, TEM techniques. Low values of grain boundary sliding and permanent continuous formation of sub-grain boundaries were found in both alloys. Significant dynamic grain growth during superplastic deformation and large value of intragranular deformation were found in the alloy without chromium. Intragranular deformation is not significant and the superplasticity is primarily a result of diffusion creep in the chromium containing alloy with Al6(Mn,Cr) particles.
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 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→τ
1
(Al
8
Cu
4
Y)+Al and the peritectic reactions Liquid+τ
6
(Al,Cu)
11
Y
3
)→Al+τ
1
(Al
8
Cu
4
Y) (612°C) and Liquid+η(AlCu)→τ
1
(Al
8
Cu
4
Y)+θ(Al
2
Cu) (595°C). The τ
1
(Al
8
Cu
4
Y) 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%.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The structure and properties of new wrought aluminum Al–4.5Cu–1.6Y–0.9Mg–0.6Mn–0.2Zr–0.1Ti–0.15Fe–0.15Si and Al–4.0Cu–2.7Er–0.8Mg–0.8Mn–0.2Zr–0.1Ti–0.15Fe–0.15Si alloys are studied. After ...homogenization and rolling, the structure is formed, which consists of the aluminum-based solid solution strengthened with fine Al
3
(Zr,Er), Al
3
(Zr,Y), and Al
20
Cu
2
Mn
3
phase particles and compact thermally stable phases of solidification origin 1–5 µm in size. The recrystallization after rolling occurs at temperatures above 350°С. As the annealing temperature increases from 400 to 550°С, the recrystallized grain size increases from 6–8 to 10–12 µm. At temperatures of 150–180°С, the hardness increases after 2-h annealing; this is related to the occurrence of aging, and the analogous effect was observed for the cast alloys of these systems. The yield strength of the Y-containing alloy subjected to 6-h annealing at 150°С is 405 MPa; in this case, the relative elongation is 4.5%. As the annealing temperature increases to 210°С, the yield strength of the both alloys decreases to 300 MPa, whereas the relative elongation remains unchanged. In the case of the alloys quenched after rolling and subsequently aged at 210°С, the yield strength of 264–266 MPa and ultimate tensile strength of 356–365 MPa are reached at a relative elongation of 11.3–14.5%. As a result, the new wrought Al–Cu–Y- and Al–Cu–Er-based alloys provide competition for the available industrial alloys.
Low plasticity is a key drawback limiting the widespread use of bulk metallic glasses. Although heat treatment and thermo-mechanical processing techniques are not applied to metallic glasses (only to ...supercooled liquids), since heating leads to embrittlement either due to structural relaxation or thermal crystallization, in this paper, we demonstrate a strong positive effect of cold rolling and subsequent thermal annealing below the glass-transition temperature on room-temperature mechanical properties of a Zr62·5Cu22·5Fe5Al10 glassy alloy. As a result we observed mechanical softening and appearance of tensile ductility (up to 1.5%) in bulk samples and an increase in hardness by up to 25% in ribbon samples yet retaining good bending plasticity. We believe that the proposed method can be applied to a number of metallic glasses.
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•Nanoscale (∼7 nm) glassy particles in a metallic glassy phase.•Supreme mechanical properties of these materials.•Solid state thermo-mechanical processing below the glass-transition temperature.•Tensile ductility (up to 1.5%) in bulk samples.•hardening without embrittlement in ribbon samples.
The evolution of the microstructure and mechanical properties of quasibinary Al–6.5Cu–2.3Y and Al–6Cu–4.05Er alloys during homogenization and subsequent thermomechanical treatment has been studied in ...this work. The Cu concentration in the aluminum solid solution increases during homogenization before quenching owing to the dissolution of a nonequilibrium excess of phases of crystallization origin and is 1.8 and 2.3% for the alloys containing Y and Er, respectively. The size of intermetallic phases in the Al–6.5Cu–2.3Y and Al–6Cu–4.05Er alloys homogenized at 605°С for 3 hours is 1.2 and 0.75 μm, respectively, and does not increase significantly with an increased annealing time. The Al–6Cu–4.05Er alloy is less prone to softening during annealing after rolling than the Y-containing alloy. This is explained by a greater degree of alloying of the aluminum solid solution (Al) and by a greater degree of dispersity of phases of crystallization origin. However, because of the same factor, the Er-containing alloy has a higher inclination to recrystallization and thereby a coarser recrystallized grain. As a result, the Al–6Cu–4.05Er alloy demonstrates higher mechanical tensile characteristics, especially after annealing at temperatures above 150°С.
