Solute clustering in Al–Cu–Mg alloys during the early stages of elevated temperature ageing

Marceau, Ross K. W.; Sha, Gang; Ferragut, R.; Dupasquier, A.; Ringer, Simon P.

doi:10.1016/j.actamat.2010.05.020

Cited by 206 publications

(117 citation statements)

References 61 publications

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“…The Guinier radius stay roughly constant as the temperature decreases and is in the range of $0.35 nm (Q1) to $0.5 nm (Q3) at the end of the quenching. This refers to a cluster number density in the range of 2 Á 10 25 m 3 (Q2) to 1 Á 10 26 m 3 (Q1), which corresponds reasonably well with the cluster densities reported in references [3,4].…”

Section: Introductionsupporting

confidence: 67%

“…The first stage is defined by a fast initial increase in strength, which is known as rapid hardening. It was shown by 3D atom probe tomography (APT) and small-angle X-ray scattering (SAXS) experiments that the rapid hardening is associated with the formation of Cu-Mg clusters [1][2][3][4]. The second rise to peak hardness is generally ascribed to the formation of the equilibrium S phase (Al 2 CuMg) [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…The chemical composition of the Cu-Mg clusters was taken as 2/3 Mg, 1/3 Cu (at.) [3,4] to calculate the electron density contrast. The uncertainties of the volume fraction calculations cannot be expected to be better than ±10% due to the uncertainties related to the absolute intensity calibration, the extrapolations of the data to 0 and infinity, and the assumptions of the chemical composition of the clusters [17].…”

Section: Introductionmentioning

confidence: 99%

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Early cluster formation during rapid cooling of an Al–Cu–Mg alloy: In situ small-angle X-ray scattering

et al. 2015

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a b s t r a c tThe formation of Cu-Mg clusters in an Al-Cu-Mg aluminum alloy is observed by small-angle X-ray scattering during cooling. Cooling rates are choosen to mimic the different conditions obtained at the surface and in the center of large forgings. Clusters of 0.45 nm start to form at 250°C. Their volume fraction depends strongly on the cooling rate and the amount of excess vacancies. The difference in cluster kinetics explains the difference in rapid hardening across large forgings.Ó 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.Age-hardenable Al-Cu-Mg alloys are widely used for aerospace and engineering applications owing to their high specific strength and good corrosion resistance. Their age hardening response is characterized by two distinct stages. The first stage is defined by a fast initial increase in strength, which is known as rapid hardening. It was shown by 3D atom probe tomography (APT) and small-angle X-ray scattering (SAXS) experiments that the rapid hardening is associated with the formation of Cu-Mg clusters [1][2][3][4]. The second rise to peak hardness is generally ascribed to the formation of the equilibrium S phase (Al 2 CuMg) [4,5].For industrial applications, the Al-Cu-Mg alloys are commonly processed as large components such as forgings or plates. The mechanical properties are tailored by the age-hardening treatment, which also involves a quenching step. Thermal gradients decrease from the surface to the center and give rise to residual stresses (RS) [6]. The magnitude of the as-quenched RS can be very high and even exceed the as-quenched strength of the materials [6,7]. In the case of Al-Zn-Mg-Cu alloys, the high as-quenched RS are caused by the formation of fine hardening precipitates that form during quenching of large components and thereby increase the yield strength of the material [8,9].In order to predict the RS formation in industrial components during quench, the changes of the nanostructure during cooling conditions close to industrial practice needs to be characterized as they highly impact the yield strength and thus the internal stress generation. Further, the influence of excess vacancies on precipitation during cooling needs to be explored. This can be done by adapting the cooling rates at high temperature, which influence the excess vacancy concentration due to annihilation on defects.SAXS is a useful tool to monitor precipitation phenomena during fast time and temperature changes given that a sufficiently high electron density contrast between the precipitate and matrix exists [4,8,10]. SAXS provides the means to collect information on the size and volume fraction of the precipitates that can then be directly compared to predictions of thermodynamic-based precipitation models [11,12]. These models can be coupled with macroscopic finite-element RS simulations to better predict the residual stress formation during the processing of industrial components [9,13] as part of through-process modeling.This work investigates the Cu-Mg cluster ...

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Section: Introductionsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Early cluster formation during rapid cooling of an Al–Cu–Mg alloy: In situ small-angle X-ray scattering

et al. 2015

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“…The combination of transmission electron microscopy (TEM) and atom probe tomography (APT) enables researchers to relate the atomic structure and composition of nanoscale features of interest and has been gaining influence over the past decades. Typically, correlative TEM/APT analyses have been carried out from distinct specimens from the same alloy, [1][2][3][4][5][6][7] which fails in cases where the microstructure is inhomogeneous and/or when targeting rare microstructural features for both TEM and APT investigations. As recently reviewed by Herbig,8 full electron microscopy characterization of specific features can be carried out on needle-shaped specimens prior to APT analysis by utilizing specially designed holders.…”

Section: Introductionmentioning

confidence: 99%

Correlative Microscopy—Novel Methods and Their Applications to Explore 3D Chemistry and Structure of Nanoscale Lattice Defects: A Case Study in Superalloys

Makineni

Lenz

Kontis

et al. 2018

JOM

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“…Imago Visualization and Analysis Software (IVAS TM ) in combination with advanced calibration techniques was used in APT data reconstruction and visualization [23,24]. The maximum separation algorithm was employed for cluster identification [7], with Mg, Si and Cu as clustering solutes, a separation distance of 0.6 nm, a surrounding distance of 0.5 nm to include all other elements, and the minimum cluster size of n = 10 to reduce the effect of small solute clusters that exist in the alloy with solutes in a random distribution [25][26][27].…”

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confidence: 99%

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

et al. 2012

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The solute-nanostructures formed in the primary α-Al grains of a Semi-Solid Metal cast Al-7Si-0.6Mg alloy (F357) during ageing at 180°C, and the age-hardening response of the alloy have been systematically investigated using transmission electron microscopy, atom probe tomography and hardness testing. A 120-h natural pre-ageing led to the formation of solute clusters and GP zones. The natural pre-ageing slowed down the precipitation kinetics six-fold during 1 h ageing at 180°C, but this effect diminished after 4 h when the sample reached the same hardness as that without the pre-ageing treatment. It reduced the number density of β″-needles to approximately half of that formed in samples without the treatment, and postponed the peak hardness occurrence to 4 h, 4 times that of the as-quenched sample. A hardness plateau developed in the as-quenched sample between 1 h and 4 h ageing corresponds to the growth of 2 the β″ precipitates and a significant concurrent decrease of solute clusters and GP zones. The average Mg:Si ratio of early solute clusters is < 0.7 while that of GP zones changes from 0.8 to 0.9 with increasing in their size, and that of β″-needles increases from 0.9 to 1.2. β″-needles, GP zones and solute clusters are important strengthening solute nanostructures of the alloy. The partitioning of solutes and precipitation kinetics of the alloy are discussed in detail.

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Solute clustering in Al–Cu–Mg alloys during the early stages of elevated temperature ageing

Cited by 206 publications

References 61 publications

Early cluster formation during rapid cooling of an Al–Cu–Mg alloy: In situ small-angle X-ray scattering

Early cluster formation during rapid cooling of an Al–Cu–Mg alloy: In situ small-angle X-ray scattering

Correlative Microscopy—Novel Methods and Their Applications to Explore 3D Chemistry and Structure of Nanoscale Lattice Defects: A Case Study in Superalloys

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

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