References of "Lecomte-Beckers, Jacqueline"
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See detailProcessing of Ti alloys by additive manufacturing: a comparison of the microstructures obtained by laser cladding, selective laser melting and electron beam melting
Reginster, Sylvie ULiege; Mertens, Anne ULiege; Paydas, Hakan ULiege et al

in Materials Science Forum (2013), 765

Additive manufacturing processes such as laser cladding (LC) or selective laser melting (SLM) appear very promising in view of an economic near-net-shape production – and also, in the case of LC, the ... [more ▼]

Additive manufacturing processes such as laser cladding (LC) or selective laser melting (SLM) appear very promising in view of an economic near-net-shape production – and also, in the case of LC, the restoration - of complex and (almost) fully dense parts from Ti alloys. Both techniques involve the melting of a metallic powder with a laser. In the SLM process, the metallic powder is deposited layer by layer in a powder bed and then molten locally according to the desired shape, whereas in LC, the metallic powder is directly projected onto a substrate through a nozzle coaxial with the laser beam. The present research aims at comparing Ti-6Al-4V samples processed by these two techniques with reference samples produced by electron beam melting (EBM), another well established additive manufacturing process (patented by Arcam AB Company) in which a powder bed is molten locally by means of an electron beam. In all three processes, the melt pool undergoes an ultrafast cooling and solidifies very rapidly once the beam has left the area, thus giving rise to strongly out-of-equilibrium microstructures. Yet, each one of these processes also has its own specificities e.g. in terms of scanning strategy and of working atmosphere (low vacuum vs. protective Ar flow). In the present work, the microstructures obtained by these three processes have been compared in details, with a particular attention for characteristics such as porosity, grain size, and the various phases present. Since epitaxial growth of the newly deposited layer on the material previously solidified has been shown [1, 2] to exert a strong influence on the microstructure and on the resulting mechanical properties, great care has been taken to study the microstructural anisotropy associated with each one of the three processes. [less ▲]

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See detailDéveloppement d’une ailette d’obus en composite magnésium renforcé de fibres de carbone
Montrieux, Henri-Michel ULiege; Mertens, Anne ULiege; Lecomte-Beckers, Jacqueline ULiege

Report (2012)

This report describes the accomplished breakthrough for the manufacturing of long carbon fibres reinforced magnesium alloy (AZ91). Infiltration can be performed with non-equilibrium conditions such as ... [more ▼]

This report describes the accomplished breakthrough for the manufacturing of long carbon fibres reinforced magnesium alloy (AZ91). Infiltration can be performed with non-equilibrium conditions such as fibres preheating, high liquid compacting pressure and low contact times. Thanks to specific TEOS sol/gel treatment, the reached fibre rate is 60 vol.% and the measured Young's modulus of the composite is ca. 110 GPa. The presence of defects including fibre yarns misorientation, unreinforced areas seems very detrimental to the bending properties. Other advanced infiltration techniques with Al pretreatment (K2ZrF6) of fibres is also considered. [less ▲]

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See detailInfluence of Fiber Distribution and Grain Size on the Mechanical Behavior of Friction Stir Processed Mg-C Composites
Mertens, Anne ULiege; Montrieux, Henri-Michel ULiege; Lecomte-Beckers, Jacqueline ULiege et al

Conference (2012, November 12)

Short C fibers-Mg matrix composites have been produced by friction stir processing sandwiches made of a layer of C fabric stacked between two sheets of either the ductile Mg alloy AZ31B, or of the less ... [more ▼]

Short C fibers-Mg matrix composites have been produced by friction stir processing sandwiches made of a layer of C fabric stacked between two sheets of either the ductile Mg alloy AZ31B, or of the less ductile alloy AZ91D, that is capable of age hardening. It has been shown that the choice of the optimal experimental parameters for the production of sound composites was strongly dependent on the nature of the matrix. 3D X-ray tomography reveals that the fibers orient along the onion rings and that they are more or less fragmented depending on the local shear stress during the process. The fiber volume fraction is increased when the nugget volume decreases in particular for the AZ91D base material and for a high advancing speed for the AZ31B base material. The fiber volume fraction influences directly the grain size, the hardness and the tensile properties of the composites. [less ▲]

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See detailComposite Manufacturing by Friction Stir Processing
Simar, Aude; de Meester, Bruno; Delannay, Francis et al

Conference (2012, October 29)

A new solid-state process developed recently on the same principles as Friction Stir Welding (FSW), Friction Stir Processing appear as a very promising technique for the production of metal matrix ... [more ▼]

A new solid-state process developed recently on the same principles as Friction Stir Welding (FSW), Friction Stir Processing appear as a very promising technique for the production of metal matrix composites and for tailoring materials properties. In the present work, this process has been applied to two different composite systems: (i) magnesium-matrix composites reinforced with carbon fibers, and (ii) copper-matrix composites reinforced with Y2O3 powder. Process optimization and mechanical properties of the composites are discussed in both systems. [less ▲]

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See detailExperimental Characterisation of Damage Occuring during Single Point Incremental Forming of a Ferritic Steel
Mertens, Anne ULiege; Guzmán Inostroza, Carlos Felipe ULiege; Habraken, Anne ULiege et al

Poster (2012, September)

Single Point Incremental Forming (SPIF) has been developed as a new dieless process for forming metal sheets. This technique appears very promising in view of the current requirements for rapid ... [more ▼]

Single Point Incremental Forming (SPIF) has been developed as a new dieless process for forming metal sheets. This technique appears very promising in view of the current requirements for rapid prototyping and/or small series production [1]. However, inaccuracies in the shape of the processed part and material failure constitute important limiting factors for applications. In the present research, a numerical approach, based on the damage model proposed by Gurson [2], has been chosen to analyse and optimise the process, predict the material rupture and the process limit. From experimental observations of plastic deformation and ductile fracture, damage is related to the nucleation, growth and coalescence of microvoids [3]. Gurson’s model uses the volume fraction of these voids as a main variable. Hence the determination of this value is a key factor for a correct identification and validation of the model. More particularly, the present work focuses on two different methods used to experimentally characterise damage occurring during single point incremental forming of a ferritic steel. Void measurements carried out by optical microscopy combined with image analysis have been compared with porosity values obtained from density measurements based on the Archimedes’ principle [4], so as to assess the feasibility of using this method for a quick characterisation of the damage. [less ▲]

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See detailFriction Stir Processing of Magnesium Matrix Composites reinforced with Carbon Fibres: Influence of the Matrix Characteristics and of the Processing Parameters on Microstructural Developments
Mertens, Anne ULiege; Simar, Aude; Montrieux, Henri-Michel ULiege et al

in W.J.Poole, K.U.Kainer (Ed.) Proceedings of the 9th International Conference On Magnesium Alloys and their Apllications (2012, July 12)

Processing of magnesium matrix composites reinforced with C fibres by ‘liquid state’ methods such as squeeze casting are usually impaired by the poor wettability of C substrates by liquid Mg. As a ... [more ▼]

Processing of magnesium matrix composites reinforced with C fibres by ‘liquid state’ methods such as squeeze casting are usually impaired by the poor wettability of C substrates by liquid Mg. As a consequence, ‘solid state’ processes such as Friction Stir Processing (FSP) appear as very promising alternative processing routes for the production of C-Mg composites. And, more particularly, FSP of a C fabric between two sheets of the fairly ductile Mg alloy AZ31B was shown to be a simple and innovative process for a large-scale production of magnesium matrix composites reinforced with short C fibres. In the present work, FSP of a C fabric between two metal sheets or thin plates has been performed using two different Mg alloys exhibiting quite different mechanical behaviours, i.e. alloy AZ31B and the more brittle alloy AZ91D. And the effect of the matrix characteristics, along with the influence of the FSP experimental parameters such as the rotational and advancing speeds, on the microstructural changes occuring upon processing have been carefully studied. A particular attention has been given to the fragmentation and distribution of the C fibres, as well as to the recrystallisation, solutionising and precipitation processes taking place in the Mg matrix. [less ▲]

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See detailInfluence of the addition of functionalized MWCNT on mechanical properties on epoxy/carbon fiber and epoxy/carbon-aramid fiber composites
Fernandez, Carolina; Flores, Paulo; Montrieux, Henri-Michel ULiege et al

in Proceedings of the 1st Brazilian Conference on Composite Materials (2012, July)

We investigated the effect of the inclusion of carbon nanotubes (CNT) on the mechanical properties and wear behavior of epoxy/carbon and epoxy/carbon-aramid composites in this study. Epoxy/carbon and ... [more ▼]

We investigated the effect of the inclusion of carbon nanotubes (CNT) on the mechanical properties and wear behavior of epoxy/carbon and epoxy/carbon-aramid composites in this study. Epoxy/carbon and epoxy/carbon-aramid composites with 0 wt.% CNT and 0.3 wt.% CNT were manufactured by RTM, amino functionalized multi-walled CNT (MWCNT) were used to modify the matrix. Tensile, compression, two rail shear, Charpy impact tests and Pin On Disc (POD) were performed on the four composites. The EP/CAF composites showed better impact resistance than the ones containing carbon woven. The addition of CNTs improves the shear modulus in 5% for EP/CF composites and 6% for EP/CAF. The results also show that the dynamic friction coefficient is independent of the CNT content, and the specific wear rate shows no improvement with the selected test parameters. [less ▲]

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See detailProcessing of Carbon Fibers Reinforced Mg Matrix Composites Via Pre-infiltration with Al
Mertens, Anne ULiege; Montrieux, Henri-Michel ULiege; Halleux, Jacques et al

in Journal of Materials Engineering and Performance (2012), 21(5), 701-706

Mg-C composites offer a suitable alternative to Al alloys while allowing for a significant weight reduction, but their production can be impaired by the poor wettability of C substrates by Mg. In the ... [more ▼]

Mg-C composites offer a suitable alternative to Al alloys while allowing for a significant weight reduction, but their production can be impaired by the poor wettability of C substrates by Mg. In the present work, a new 'liquid' processing route has been investigated. By making use of the well-known effect of a pre-treatment of the C fibres with an aqueous solution of K2ZrF6 in favouring spontaneous wetting of C with Al, C yarns have been pre-impregnated with Al and the feasibility of further using them as reinforcements in Mg matrix composites has been assessed. More particularly, it has thus been shown that, under the thermal conditions involved in the process, C fibres did not suffer damage due to chemical reaction with Al, and also that special care should be taken in order to control the surface condition of the pre-infiltrated yarns. [less ▲]

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See detailTi alloys processed by selective laser melting and by laser cladding: microstructures and mechanical properties
Mertens, Anne ULiege; Contrepois, Quentin ULiege; Dormal, Thierry ULiege et al

in proceedings of 12th EUROPEAN CONFERENCE ON SPACECRAFT STRUCTURES, MATERIALS & ENVIRONMENTAL TESTING, Noordwijk 20-23 mars 2012 (2012, March)

Selective laser melting (SLM) and laser cladding were developed in the late 1990s as economic layer-by-layer near-net-shape processes allowing for the production – and also, in the case of laser cladding ... [more ▼]

Selective laser melting (SLM) and laser cladding were developed in the late 1990s as economic layer-by-layer near-net-shape processes allowing for the production – and also, in the case of laser cladding, the restoration - of complex parts. Both techniques involve the melting of a metallic powder with a laser. In the case of SLM, the metallic powder is deposited layer by layer and then molten locally according to the desired shape, whereas in laser cladding the metallic powder is projected onto a substrate through a tube coaxial with the laser. In both processes, the metallic melt pools then cool down and solidify very rapidly, thus producing strongly out of equilibrium microstructures that might exhibit high internal stresses. In the present work, efforts have been made to enhance the flexibility of the laser cladding process: a second laser with a maximum power of 300W was installed beside the original laser (with a higher maximum power of 2000W), thus allowing for the processing of parts with thinner walls and/or coatings. Moreover, flexibility was also improved in relation with the geometry of the parts by use of a 5-axes displacement control. Samples of alloy Ti-6Al-4V, that is widely used in the aeronautic industry due to its high specific strength, have been processed both by SLM and by laser cladding. The resulting microstructures have been characterised in details by optical microscopy, SEM and EBSD so as to allow for a better understanding of the solidification process and of the subsequent phase transformations taking place upon cooling for both techniques. The influence of processing parameters such as the orientation of the deposition of the successive powder layers on the mechanical properties was also investigated by means of uniaxial tensile testing performed on samples with different deposition orientations in regard to the direction of mechanical solicitation. Moreover, some of the samples for mechanical testing had undergone an annealing treatment at 640°C for 4 hours to relieve internal stresses, in order to assess more precisely the effect of those stresses on the tensile properties. [less ▲]

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See detailCurrent Developments of Alloyed Steels for Hot Strip Roughing Mills : Characterization of High-Chromium Steel and Semi-High Speed Steel
Lecomte-Beckers, Jacqueline ULiege; Sinnaeve, Mario; Tchuindjang, Jérôme Tchoufack ULiege

in Iron and Steel Technology (2012)

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill - high chromium steel (HCS) and semi-high-speed steel (semi-HSS), In this paper, the new semi-high-speed steel grade is studied

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See detailMicrostructure and mechanical properties of stir processed magnesium matrix composites reinforced with carbon fibres
Simar, Aude; Mertens, Anne ULiege; Montrieux, Henri-Michel ULiege et al

Conference (2012, January 26)

Mg-Al-Zn alloys have been reinforced with carbon fibres using friction stir processing (FSP) which appears as a promising alternative for the large-scale production of C-Mg composites. The process has ... [more ▼]

Mg-Al-Zn alloys have been reinforced with carbon fibres using friction stir processing (FSP) which appears as a promising alternative for the large-scale production of C-Mg composites. The process has shown its ability to produce sound composites with enhanced strength compared to the non-reinforced alloys. The C fabric is fragmented in short fibres leading to a reduction in grain size and an improved hardness. [less ▲]

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See detailDensity and porosity control of sintered 316L stainless steel parts produced by additive manufacturing
Verlee, Bruno; Dormal, Thierry ULiege; Lecomte-Beckers, Jacqueline ULiege

in Powder Metallurgy (2012), 55(4), 260-267

Additive manufacturing (AM) techniques offer the possibility to build complex geometries with integrated functionalities. Three-dimensional (3D) printing of metallic powder is probably the only AM ... [more ▼]

Additive manufacturing (AM) techniques offer the possibility to build complex geometries with integrated functionalities. Three-dimensional (3D) printing of metallic powder is probably the only AM technique that can build controlled porosity sintered parts, such as filter elements and fluid permeable components. Many building and sintering parameters can be set to adjust porous properties of the final part. The effects of particle size, paricul shape, sintering temperature and sintering time on the final properties of the sinteres parts have been analysed. Correlations have been established between these properties and process parameters [less ▲]

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