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The development of aluminum alloys with superior mechanical properties and high strain rate superplasticity is an important prerequisite for advancing applications of superplastic blow-forming technology. This study focuses on the effect of Ce and Fe additions on the microstructural parameters and tensile properties of a superplastic Al-4.8%Mg-0.6%Mn-0.15%Cr (AA5083-type) alloy. The studied alloy exhibits a bimodal particle size distribution with coarse crystallization origin inclusions and fine secondary precipitates. Both the coarse and fine particles lead to grain refinement. The coarse Ce-, Fe-, and Mn-rich intermetallic particles of crystallization origin provide evidence of a particle-stimulated nucleation effect. The semi-coherent Mn-enriched compact-shaped dispersoids with an Ashby-Brown contrast, a quasicrystalline structure, and a mean size of 38 nm are precipitated after low-temperature homogenization and exhibit a strong Zener pinning effect. The proposed thermomechanical treatment results in the development of a grain size of 4 μm and an ultimate tensile strength of 340 MPa in the recrystallized sheet. The superplastic deformation behavior in a strain rate range of 1 × 10−2 to 1 × 10−1 s−1 and the associated strain-induced changes in the grain structure and mechanical properties of the developed alloy are presented and discussed. [ABSTRACT FROM AUTHOR]

Evolution of the deformation behaviour, surface and bulk structures at superplastic flow of the АА7475 aluminium-based alloy were studied by scanning and transmission electron microscopes and a focused ion beam technique. Differences between deformation behaviour at a primary stage with strains below 0.69 and a steady stage with strains above 0.69 were discussed. The research showed the grain growth and grain elongation to the stress direction at a primary stage of deformation. Stabilisation of both mean grain size and grain aspect ratio was found at a steady stage of deformation. Grain neighbour switching, grain rotation, dispersoid free zones and some insignificant intragranular strain were observed at both stages. Appearing and disappearing of the grains on the sample surface, with increased dislocation activity occurred at the steady stage of deformation. The current results highlighted the importance of diffusion creep as a dominant mechanism at the beginning of superplastic deformation and as an accommodation mechanism of the grain boundary sliding at the steady stage of deformation. The dislocation creep as an additional accommodation mechanism of the grain boundary sliding at the steady stage of superplastic deformation is suggested. [ABSTRACT FROM AUTHOR]

Different Al-based alloys were evaluated as materials for cladding on a high-strength Al-Zn-Mg-Cu-Ni-Zr alloy with high-strain rate superplasticity. Clad sheets were fabricated by hot-roll bonding. Superplastic behaviour, mechanical properties at room temperature and corrosion properties of clad sheets were studied. The microstructure analysis and tensile results revealed that bonding was acceptable in the samples with cladding materials. The research revealed that the Al-Zn-Ca alloy provided good corrosion protection, superplasticity and a low decrease in the mechanical properties of cladded sheets. [ABSTRACT FROM AUTHOR]

The superplastic properties of two high strength aluminium alloys are investigated. The first alloy contains fine, coherent Al 3 (Zr,Sc) particles, and the second alloy contains both fine, coherent Al 3 Zr particles and coarse, eutectic Al 3 Ni particles. Due to its fine, stable grain structure, the alloy containing both Al 3 Zr and Al 3 Ni particles exhibits significantly better superplastic properties. The superplastic behaviour in tension under both constant and initial strain rates was compared, and the effective activation energy of superplastic deformation was calculated. The alloy containing both fine and coarse particles exhibit 1100%–1200% elongation at strain rates of 1 × 10 −2 s −1 –1 × 10 −1 s −1 and temperature of 440 °C. [ABSTRACT FROM AUTHOR]

The influence of homogenisation regimes on precipitations of fine Mn-bearing dispersoids, recrystallisation kinetics, grain structure, mechanical properties and superplasticity of cold worked sheets of Al-3Mg alloys with Mn, Cr and Zr is studied. Precipitates of coherent compact and plate-like particles of Mn-bearing phase are found after homogenisation annealing. Activation parameters of the low-temperature internal friction, internal friction solute grain boundaries peak and dislocation nature thermally activated relaxation peak in the samples treated by different regimes are compared. High-temperature homogenisation at 460 °C provides a higher volume fraction and finer particles of Mn-containing phases after thermomechanical processing compared to low temperature treatment at 380 °C. Consequently, finer grains and higher superplasticity indicators are achieved in a recrystallised state. Polygonisation is observed during heating of the cold worked samples pre-homogenised at 380 °C: recrystallisation temperature is increased and mechanical strength at room temperature is improved. [ABSTRACT FROM AUTHOR]

Superplastic deformation behaviour of two aluminium-based AA7XXX type alloys with Sc and Zr additives distinguished by the presence and absence of coarse eutectic Al 9 FeNi particles are compared. An alloy with Al 9 FeNi particles exhibits high strain rate superplasticity at constant strain rate range of 5×10 −3 –8×10 −2 s −1 with elongation of 915% due to extensive dynamic recrystallisation. Effective activation energy of superplastic deformation, surface relief of deformed samples, and grain structure evolution are analysed. Particle-depleted zones are found in the alloy with Al 9 FeNi particles at strains higher than 1.25. [ABSTRACT FROM AUTHOR]

Highlights: [•] 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. [Copyright &y& Elsevier]

Abstract: Aluminium alloys containing eutectic particles of the Al–Ni, Al–Mg–Si, Al–Ni–Ce and Al–Cu–Ce systems are investigated. The particles which control grain growth and stimulate grain nucleation are studied. The Zener–Smith law about dependence between grain size and particle parameters is confirmed and experimental coefficients are found. Experimental coefficients of the Zener–Smith equation obtained in this study depend on the particle size and differ from theoretical coefficients proposed by Zener and Smith. Some alloys with grain size about 3μm demonstrate very good superplasticity indicators, namely: the strain rate sensitivity index m =0.5–0.6 and the elongation over 400% at constant strain rate 5×10−3 s−1. [Copyright &y& Elsevier]

The development of Al–Mg–Si-based alloys with advanced superplasticity and improved mechanical properties is an important task for further applications of superplastic blow-forming technology in the production of complex-shape parts. The current study focuses on the influence of eutectic forming Ni and Fe and dispersoid forming Sc and Zr alloying elements on the microstructural evolution, superplastic behavior, and tensile properties at room temperature for the Al-1.2%Mg-0.7%Si-1.0%Cu (AA6013-type) alloy. The X-Ray diffraction, scanning, and transmission electron microscopy were used for microstructural characterization. The bimodal particle size distribution was observed after the thermomechanical treatment of the alloy studied. The high density of the L1 2 coherent dispersoids with a mean size of 10 ± 1 nm providing a significant Zener pinning effect was formed during homogenization annealing. The near-equiaxed coarse particles with a size in a range of 0.5–5.0 μm belonged pre-dominantly to the Mg 2 Si and Al 9 FeNi phases, which led to an important particle-stimulated nucleation (PSN) effect. The alloys studied exhibited a superplastic behavior in temperature and strain rate limits of 440–520 °C and 1 × 10−3 s−1 - 1 × 10−2 s−1, respectively, with an elongation-to-failure range of 350–480%. The age-hardening heat treatment provided a yield strength of 370 ± 4 MPa, an ultimate tensile strength of 415 ± 2 MPa, and elongation of 6 ± 1%. • The novel alloy exhibits superplasticity in a strain rate range of 10−3-10−2 s−1. • The alloy studied exhibits an increased room temperature strength. • The particle-stimulated nucleation occurs due to Al 9 FeNi and Mg 2 Si phases. • The L1 2 Al 3 (Sc,Zr) dispersoids provide significant Zener pinning effect. [ABSTRACT FROM AUTHOR]

Rare-earth elements improve the mechanical properties of aluminum owing to the formation of the L1 2 -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 Al 3 (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 L1 2 -Al 3 (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. [ABSTRACT FROM AUTHOR]

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 Al 3 (Zr,Y) dispersoids was observed during a homogenization treatment. The precipitates have an L1 2 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. [ABSTRACT FROM AUTHOR]

Highlights: [•] Increase in Mg contents improves superplasticity indicators in the Al–Mg–Mn–Cr alloy. [•] Differences in the Al–Mg alloys with and without chromium are observed. [•] The new Al–6.3Mg–0.7Mn–0.3Cr alloy obtained using rolling and heat treatment . [ABSTRACT FROM AUTHOR]

• Minor additions of Y, Sc and Zr significantly refined the as-cast grain in AA6013 alloy. • The annealing of as-cast material initiates continuous and discontinuous precipitation of L1 2 -phase. • The L1 2 -dispersoids inhibited recrystallization and grain growth due to Zener pinning effect. • The coarse Y-bearing particles of eutectic origin provide PSN effect during recrystallization. • The superplasticity is observed due to inhibited grain growth and PSN effect. Alloy AA6013 (Al-Mg-Si-based aluminum alloy) is of particular interest to the aerospace and automotive industries because of its attractive combinations of properties, however, accelerated grain growth at elevated temperatures limits its superplastic formability. The motivation for this study was to refine grain structure and control grain growth at elevated temperature in order to eliminate the lack of superplasticity in the alloy. For this reason, minor additions of Y, Sc, Zr were considered and their influence on the microstructural evolution, superplastic deformation behavior, and room temperature mechanical properties of a novel AA6013-type alloy was studied. A noticeable refinement of as-cast grain structure was observed due to the co-effect of Sc, Zr, Y additions. It was demonstrated that the Mg 2 Si phase and Y-bearing phases were formed during solidification of the studied alloys. The phases of silidification origin were fragmented during thermo-mechanical treatment led to the near uniform distribution of coarse particles of 0.5–0.8 µm size in the matrix. The coarse particles caused grain refinement during the superplastic deformation due to the particle stimulated nucleation (PSN) effect. In the alloy containing yttrium, during the decomposition of the aluminum-based solid solution supersaturated by Y, Zr, Sc, the following two precipitation mechanisms were involved: continuous precipitation resulting in the formation of nanoscale L1 2 phase dispersoids distributed homogeneously throughout the aluminum matrix and discontinuous precipitation that caused fan-shaped aggregations of the same phase near the high-angle grain boundaries. The nanoscale continuously-formed dispersoids retarded the recrystallization and dynamic grain growth during superplastic deformation due to Zenner pinning mechanism. Both PSN and Zenner pinning effects led to the grain refinement and achievement of superplasticity. The maximum elongation of 470% was observed under the test condition of T = 520 °C and ɛ. = 1 × 10−3 − 5 × 10−2 s −1. The room temperature tensile test revealed the following maximum characteristics of the sheet of the alloy with Y additions: yield strength of 330 MPa, ultimate tensile strength of 375 MPa, and elongation at fracture of 10%. [ABSTRACT FROM AUTHOR]

Minor additions of rare-earth elements improve the mechanical properties of aluminum-based alloys due to precipitation strengthening, increased recrystallization resistance, and grain refinement effects. This study investigated the microstructure, room temperature mechanical properties, and superplasticity of Al–Mg–Z–Er alloys with the Mg content in a range of 2.1–4.9 wt%. The alloys' microstructure was presented by an Al-based solid solution matrix enriched with Mg, the (Al,Mg) 3 Er phase of solidification origin, and nanoscale secondary precipitates of the Al 3 (Er,Zr) L1 2 –structured phase. The Al 3 (Er,Zr) precipitates provided the Orowan strengthening mechanism, led to a strong recrystallization resistance and the Zener pinning effect during elevated temperature deformation. An increase of the Mg solute resulted in a solid solution strengthening and facilitated dynamic recrystallization at elevated temperatures. In the alloy with 4.9%Mg, a combined effect of fine L1 2 precipitates, high solute Mg, and (Al,Mg) 3 Er particles led to a fine-grained structure formation and superplasticity with the maximum strain rate sensitivity m of 0.51 and the elongation-to-failure of 550–600% at the constant strain rates of (0.8–1) × 10−2 s−1. The mechanical properties at room temperature were studied after the post-deformation annealing of the thermomechanically treated alloys and after the superplastic deformation. The developed Arrhenius-type mathematical model of superplastic deformation behavior showed excellent predictability for the studied alloys with different solute Mg. [Display omitted] • Microstructure and tensile properties for thermomechanical-treated Al–Mg–Er–Zr alloys were studied. • A L1 2 -Al 3 (Er,Zr) precipitates parameters were studied after annealing of as-cast and rolled samples. • Increase in Mg solute improved solid solution strengthening and superplastic properties. • Model with excellent predictability of the superplastic deformation behavior was developed. [ABSTRACT FROM AUTHOR]