The crystal structure of the β′ phase in Al–Mg–Si alloys

Vissers, R.; Huis, Marijn A. van; Jansen, J.C.; Zandbergen, H.W.; Marioara, Calin Daniel; Andersen, Sigmund Jarle

doi:10.1016/j.actamat.2007.02.032

Cited by 408 publications

(200 citation statements)

References 21 publications

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“…One could think that the columns with weaker intensity contain vacancies or other elemental species. However, Si columns in other precipitate phases such as β' and B' have been found to have a shorter repeat distance than a Al , in the form n/(n+1) × a Al for some whole number n (n = 3 for β' (Vissers et al, 2007) and n = 5 for B' . This generates a superstructure in the main growth direction (normal to the imaged planes in this work), with a lattice parameter of n × a Al .…”

Section: Chemistry In the Mapped Precipitatesmentioning

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: Chemistry In the Mapped Precipitatesmentioning

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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“…[6] the molar volume V m of the clusters is assumed to be constant and equal to the value used for the hardening precipitates in NaMo-Version 1 (i.e., 7.62 9 10 À5 m 3 /mol). [21,22,28,29] Then, when V m is fixed, the cluster/matrix interfacial energy c c is adjusted so that Eq.…”

Section: Correction Term For the Reduced Thermodynamic Stability Of Cmentioning

confidence: 99%

“…[1][2][3] Because the former strength contribution is by far the most important one, the precipitation sequence and resulting strength evolution occurring during natural and artificial aging of the alloys have been extensively investigated and reported upon in the scientific literature. [4][5][6] In addition, the chemical composition and atomic structure of the clusters and hardening precipitate which form have been studied in detail by means of various high-resolution experimental techniques along with atomistic modeling. [7][8][9][10] Obviously, some of these works must be said to be at the leading edge of international materials research, which gives aluminum a competitive advantages compared to other structural and functional materials that are not so thoroughly examined.…”

Section: Introductionmentioning

confidence: 99%

An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages

Myhr

Grong

Schäfer

2015

Metall Mater Trans A

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In this article, a new age-hardening model for Al-Mg-Si alloys is presented (named NaMo-Version 2), which takes into account the combined effect of cold deformation and prolonged room-temperature storage on the subsequent response to artificial aging. As a starting point, the original physical framework of NaMo-Version 1 is revived and used as a basis for the extension. This is permissible, since a more in-depth analysis of the underlying particle-dislocation interactions confirms previous expectations that the simplifying assumption of spherical precipitates is not crucial for the final outcome of the calculations, provided that the yield strength model is calibrated against experimental data. At the same time, the implementation of the Kampmann-Wagner formalism means that the different microstructure models can be linked together in a manner that enforces solute partitioning and competition between the different hardening phases which form during aging (e.g., clusters, b¢¢ and b¢). In a calibrated form, NaMo-Version 2 exhibits a high degree of predictive power, as documented by comparison with experiments, using both dedicated nanostructure and yield strength data as a basis for the validation. Hence, the model is deemed to be well-suited for simulation of thermomechanical processing of Al-Mg-Si alloys involving cold-working operations like sheet forming and stretch bending in combination with heat treatment and welding.

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“…The precipitate needles obstruct dislocations, consequently increasing the material strength. The needles in 6xxx alloys mainly consist of Mg and Si in addition to Al itself [1] [2] [3], but other added elements may enter the precipitates as well. Elements like Li, Cu, Zn, Ag and Ge have proven to be beneficial for the nucleation and growth of precipitates, and they have consequently been added in multiple combinations and amounts [4] [5] [6] [7] [8].…”

Section: Introductionmentioning

confidence: 99%

Atomistic details of precipitates in lean Al–Mg–Si alloys with trace additions of Ag and Ge studied by HAADF-STEM and DFT

Mørtsell

Andersen

Friis

et al. 2017

Philosophical Magazine

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Bonding energies and volume misfits for alloying elements and vacancies in multicomponent Al-Mg-Si alloys have been calculated using density functional theory and the results have been compared with numbers obtained by atomic scale precipitate structure analysis, using high angle annular dark-field scanning transmission electron microscopy. The techniques in combination provide new insight into precipitation in these alloys. In the Ge containing alloy were found two new stacking configurations of the well-known strengthening phase β". In the alloy with Ag a new Q'/C -like local configuration containing Ag was discovered, and a model has been proposed. The experimental results are justified by simulations.

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The crystal structure of the β′ phase in Al–Mg–Si alloys

Cited by 408 publications

References 21 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

An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages

Atomistic details of precipitates in lean Al–Mg–Si alloys with trace additions of Ag and Ge studied by HAADF-STEM and DFT

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