In situ X-ray tomography observation of inhomogeneous deformation in semi-solid aluminium alloys

Terzi, S.; Salvo, Luc; Suéry, M.; Limodin, Nathalie; Adrien, Jérôme; Maire, Éric; Pannier, Yannick; Bornert, Michel; Bernard, D.; Felberbaum, M.

doi:10.1016/j.scriptamat.2009.04.041

Cited by 117 publications

(94 citation statements)

References 14 publications

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“…Recent advances in materials characterization can be attributed to developments in three-dimensional visual-ization using computerized serial sectioning, X-ray microtomography, and focused ion beam (FIB) techniques, and this type of characterization is increasingly applied in studies on nucleation, [11] growth, [12] coarsening, [13] deformations, [14] and phase formation. [15] Only a few tomographic investigations have been performed on the b phases in concentrated AlSi alloys (i.e., the studies by Terzi, [16] Dinnis, [17] Timpel [18] and Puncreobutr [19] ).…”

Section: Introductionmentioning

confidence: 99%

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Mikołajczak

Ratke

2014

Metall Mater Trans A

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The presence of Fe aids in establishing the mechanical and physical properties of AlSi alloys and is also one of the main impurities leading to formation of b-Al 5 FeSi intermetallics. This study aims to understand the effect of fluid flow on the dendritic microstructure with intermetallics in Al-5/7/9 wt pct Si-0.2/0.5/1.0 wt pct Fe alloys that are directionally solidified under defined thermal and fluid flow conditions. We made extensive use of 3D X-ray tomography to obtain a better insight into the morphology and formation of the intermetallics. Three-dimensional (3-D) distribution of intermetallics presented here shows that the growth of large b-Al 5 FeSi due to forced flow occurs in the eutectic specimen center and together with an increase in the number density of b precipitates. The 3D reconstructions have verified the b shaped to be curved, bent with twining, branched, and to have imprints, holes, and propeller-shaped platelets. The 3D views showed that hole-shaped b arose from the lateral growth around a-Al dendrites. These views also confirmed the phenomenon of shortening of b as an effect of flow in the dendritic region, where b could be fragmented or completely remelted, and ultimately resulting in microstructures with shorter b-Al 5 FeSi and increases in number density. The analysis revealed an interaction between melt flow, 3D distribution, and the morphology of b-Al 5 FeSi. The growth of a large and complex group of b intermetallics can reduce the melt flow between dendrites and strengthen pore nucleation and eutectic colonies nucleation, leading to lower permeability of the mushy zone and increased porosity in the castings.

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Section: Introductionmentioning

confidence: 99%

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Mikołajczak

Ratke

2014

Metall Mater Trans A

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“…Nowadays, submicron resolution can easily be achieved on most synchrotron X-ray tomography beamlines. Combined with increasingly fast data acquisition systems, these techniques allow in situ microtomography observations of solidifying microstructures [14], even under tensile deformation [15].…”

Section: Introductionmentioning

confidence: 99%

Curvature of micropores in Al–Cu alloys: An X-ray tomography study

Felberbaum

Rappaz

2011

Acta Materialia

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Micropores formed in Al-Cu alloys cast under controlled conditions have been analyzed using high-resolution X-ray tomography. The influence of inoculation conditions, copper content, cooling rate and initial hydrogen content on the morphology of pores has been investigated. Based on the three-dimensional reconstructed shape of the pores, the distribution of curvature was estimated. It is shown that the mean curvature of pores in either non-inoculated or inoculated Al-4.5 wt.%Cu alloys can be as large as 0.35 lm À1 near the end of solidification and can be fairly well approximated by a set of interconnected cylinders growing in between the primary phase dendrites. The so-called "pinching" effect, i.e. the restriction of the pore curvature by the solid network, is a function of the volume fraction of the primary phase and of the secondary dendrite arm spacing. If the fraction of porosity is highly dependent on the initial hydrogen content, the curvature itself is only weakly influenced by this parameter. Based on these results, it is concluded that curvature plays a major role in porosity models and that the analytical pinching model developed by Couturier et al.[1] offers a fairly good and simple approximation of this contribution.

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“…The segmentation is the designation of all the phases of the multiphase domain, using the grey level of the tomography images. Because images are already segmented by Terzi et al [5], only generations of surface and volume mesh will be explained here.…”

Section: Finite Element Representationmentioning

confidence: 99%

“…This imaging technique gives access to in situ three-dimensional (3D) morphology of a multiphase sample. Thus, Terzi et al obtained a set of 3D images showing morphological evolutions in a few millimeters sample of an aluminium copper alloy during tensile testing [5]. It is currently possible to reach a spatial and time resolution of less than 1 µm and 1 s, respectively, on millimeters domain size [4].…”

Section: Introductionmentioning

confidence: 99%

Numerical tensile test on a mushy zone sample

Zaragoci¹,

Silva²,

Bellet³

et al. 2012

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Time sequences of 3D images of an Al-Cu alloy in the mushy state are obtained using in situ and real-time X-ray microtomography during a tensile test. Surface meshes of phase interfaces are built from these images with the help of a Marching Cubes algorithm. The signed distance to the surface meshes is then computed on a finite element mesh of the volume of the phases. These signed distance functions enable to track the interfaces between the phases in an implicit way. A numerical representation of the real microstructure is thus obtained, allowing to perform a numerical tensile test which is compared with the experimental tensile test. Results retrieve the general dynamic behaviour of the strain field evolution and opens promising perspectives for further interpretations of experimental results based on numerical simulations. IntroductionNowadays, numerical simulations of complex systems are mandatory in many fields. The first aspect to consider for performing analyses on such system is the creation of a realistic numerical representation of the object under study. This is the case in phase transformations taking place in the context of materials science. Several phases may coexist in a given material, delimited by interfaces. A mesh of the structure of the phases is then needed to study the heat, mass and momentum transfers taking place at phase interfaces and in the bulk phases. Results of such analyses for the entire material are not trivial because of the various phase properties and interface behaviours.When it is not possible to consider a numerical representation of the real specimen, statistical representative elementary volumes (REV) can be used. Advantages lead in the possibility to easily change the morphology of the REV. The sample behaviour can then be studied with respect to various parameters. For instance, by using a modified Voronoi tessellation, Phillion et al. showed the effect of microstructural features on the semi-solid tensile deformation of an aluminium alloy such as solid fraction, porosity and grain size [1].During the last decade, X-ray microtomography has considerably developed [2][3][4]. This imaging technique gives access to in situ three-dimensional (3D) morphology of a multiphase sample. Thus, Terzi et al. obtained a set of 3D images showing morphological evolutions in a few millimeters sample of an aluminium copper alloy during tensile testing [5]. It is currently possible to reach a spatial and time resolution of less than 1 µm and 1 s, respectively, on millimeters domain size [4].The ambition of this paper is to describe a way to transform data coming from X-ray microtomography into a finite element (FE) representation and to use it to run numerical simulations. In section 2, the approach chosen to obtain the FE representation is explained. Section 3 presents the model equations for the numerical tensile test and the way to solve them. Finally, results on the real morphology are presented and compared to the experimental data in section 4.

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In situ X-ray tomography observation of inhomogeneous deformation in semi-solid aluminium alloys

Cited by 117 publications

References 14 publications

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Curvature of micropores in Al–Cu alloys: An X-ray tomography study

Numerical tensile test on a mushy zone sample

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