Influence of alloy composition and heat treatment on precipitate composition in Al–Zn–Mg–Cu alloys

Marlaud, T.; Deschamps, A.; Bley, F.; Lefebvre, W.; Baroux, B.

doi:10.1016/j.actamat.2009.09.003

Cited by 391 publications

(173 citation statements)

References 32 publications

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“…In this work, such symmetry averaging is shown to create atomic-resolution EDS maps of nanometer-sized precipitate structures in aluminium alloys. This is a great advancement from composition measurements utilizing lower-magnification EDS mapping or atom-probe tomography (Marlaud et al, 2010;Li et al, 2014), where the atomic structure cannot be resolved. With most atomically resolved spectroscopy being demonstrated on highly stable model systems such as SrTiO 3 , an application to engineering alloys used in bikes, cars and airplanes should be of broader interest to materials scientists.…”

Section: Introductionmentioning

confidence: 99%

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Wenner

Jones

Marioara

et al. 2017

Micron

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Scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDS) is a common technique for chemical mapping in thin samples. Obtaining high-resolution elemental maps in the STEM is jointly dependent on stepping the sharply focused electron probe in a precise raster, on collecting a significant number of characteristic X-rays over time, and on avoiding damage to the sample. In this work, 80 kV aberration-corrected STEM-EDS mapping was performed on ordered precipitates in aluminium alloys. Probe and sample instability problems are handled by acquiring series of annular dark-field (ADF) images and simultaneous EDS volumes, which are aligned and non-rigidly registered after acquisition. The summed EDS volumes yield elemental maps of Al, Mg, Si, and Cu, with sufficient resolution and signal-to-noise ratio to determine the elemental species of each atomic column in a periodic structure, and in some cases the species of single atomic columns. Within the uncertainty of the technique, S and β'' phases were found to have pure elemental atomic columns with compositions Al 2 CuMg and Al 2 Mg 5 Si 4 , respectively. The Q' phase showed some variation in chemistry across a single precipitate, although the majority of unit cells had a composition Al 6 Mg 6 Si 7.2 Cu 2 .

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Section: Introductionmentioning

confidence: 99%

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Wenner

Jones

Marioara

et al. 2017

Micron

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“…Strength and ductility are equally important in the damage tolerance and durability [7,8]. Precipitation hardening plays an important role in strengthening the 7XXX aluminum alloys [9]. Increasing the additions of Zn and Mg will enhance the volume fraction of precipitates and improve the mechanical properties [10].…”

Section: Introductionmentioning

confidence: 99%

Hot Deformation Behavior of a Spray-Deposited Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr Alloy

Sheng

Lei

Xiao

et al. 2017

Metals

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Abstract:Metallic materials have a significant number of applications, among which Al alloys have drawn people's attention due to their low density and high strength. High-strength Al-based alloys, such as 7XXX Al alloys, contain many alloying elements and with high concentration, whose microstructures present casting voids, segregation, dendrites, etc. In this work, a spray deposition method was employed to fabricate an Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr (wt %) alloy with fine structure. The hot deformation behavior of the studied alloy was investigated using a Gleeble 1500 thermal simulator and electron microscopes. The microstructure evolution, variation in the properties, and precipitation behavior were systematically investigated to explore a short process producing an alloy with high property values. The results revealed that the MgZn 2 particles were detected from inside the grain and grain boundary, while some Al 3 Zr particles were inside the grain. An Arrhenius equation was employed to describe the relationship between the flow stress and the strain rate, and the established constitutive equation was that: Figure 7 gives the hardness variations of the hot compressed samples aged at 120 • C fo durations. For the samples after being hot-compressed at strain rates of 1 s −1 and 0.001 s −1 , present the same trend. The initial hardness of compressed samples increased with the hot de temperature. The hardness of the hot-compressed samples increased with the aging time, a kept constant as they were aging at certain temperatures for 15 h.Metals 2017, 7, 299 deformation temperature. The hardness of the hot-compressed samples increased with the and almost kept constant as they were aging at certain temperatures for 15 h. Discussion Constitutive EquationThe constitutive relationships were used to describe the hot deformation behavior. Som are employed to reveal the hot deformation behavior, in which one of the most extended v the hot working constitutive equation is as follows [24]:where ε is the strain rate; A is a material constant which is independent of temperature true stress; Q is the activation energy; R is the gas constant (8.31); and T is the absolute tem (K). At low stress lever (ασ < 0.8):At high stress lever (ασ > 1.2):(σ) σ n F  , β and n are the material constants, α = β/n. Substituting Equations (2) and (3) (4) and (5), respectively, gives:The values of n and β are from the slopes of the lines in ln ε and σ, lnε and ln σ , Discussion Constitutive EquationThe constitutive relationships were used to describe the hot deformation behavior. Som are employed to reveal the hot deformation behavior, in which one of the most extended v the hot working constitutive equation is as follows [24]:where .ε is the strain rate; A is a material constant which is independent of temperature; σ is stress; Q is the activation energy; R is the gas constant (8.31); and T is the absolute tempera At low stress lever (ασ < 0.8):At high stress lever (ασ > 1.2): F(σ) = σ n , β and n are the material constants, α = β/n. Substit...

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“…The metastable precursor phases [12,13,14] all form on {111} Al planes with a disc-shaped morphology. The chemical compositions of η-type precipitates in a peak-aged 7449 alloy was studied by atom-probe tomography [15], and was estimated to (atomic fraction) 42% Zn, 7% Cu, 33% Mg and 18% Al. Atomically resolved electron energy loss spectroscopy (EELS) measurements of precipitates in the same alloy revealed that Cu atoms are replacing Zn atoms, and that this replacement has no preference for any specific Zn sites, e.g.…”

Section: Introductionmentioning

confidence: 99%

Precipitation in a mixed Al–Cu–Mg/Al–Zn–Mg alloy system

Wenner

Friis

Marioara

et al. 2016

Journal of Alloys and Compounds

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The precipitation-hardened alloy systems Al-Cu-Mg (2xxx) and Al-Zn-Mg (7xxx) were compositionally combined from a base alloy containing 2% Cu and 1% Mg, added 1-4% Zn (weight fractions). Precipitates in these alloys were studied in their peak-aged states by scanning transmission electron microscopy, focusing on qualitative and quantitative compositional measurements using energy-dispersive X-ray spectroscopy mapping. An alloy with 2.5 wt.% Zn contained both the hardening S phase from the 2xxx system and η-type phases from the 7xxx system, while alloys with 1% and 4% Zn were dominated by respectively S and η-type precipitates. The elements Mg, Cu and Zn were always present in both phases, suggesting a modification of the compositions they assume in their "native" alloy systems. Density functional theory calculations were used to investigate which atomic sites were most prone to an elemental replacement. For the η-type precipitates, calculations show that a Cu → Zn substitution leads to a decrease in formation enthalpy up to Zn/(Cu+Zn) ≈ 25%, which agrees well with the experimental results. For the S phase, an Al → Zn substitution was found to be the most favorable, although this increases the formation enthalpy slightly.

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Influence of alloy composition and heat treatment on precipitate composition in Al–Zn–Mg–Cu alloys

Cited by 391 publications

References 32 publications

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Hot Deformation Behavior of a Spray-Deposited Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr Alloy

Precipitation in a mixed Al–Cu–Mg/Al–Zn–Mg alloy system

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