References of "Lecomte-Beckers, Jacqueline"
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See detailRole of impurities in reclaimed WC-TaC-TiC-Co powders used in cutting tools.
Magnée, Adrien ULg; Lecomte-Beckers, Jacqueline ULg

in Proceedings of the International Conference on Advances in Hard Materials Production (1992)

The purpose of the present work was to examine the effect of recycling and the effect of intentional impurities (CaS, Al2O3, Zn, SiO2) on some properties (transverse rupture strength, hardness and cutting ... [more ▼]

The purpose of the present work was to examine the effect of recycling and the effect of intentional impurities (CaS, Al2O3, Zn, SiO2) on some properties (transverse rupture strength, hardness and cutting tests) of WC-TaC-TiC-Co. In all cases the batches of powders were processed under identical conditions with sintering carried out in laboratory. Damage study of the sintered carbides plates during cutting tests have been interpretated following the Taylor's law, relating the tool lifes as a function of cutting speed. [less ▲]

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See detailElectron microscopical investigations of hexagonal phase precipitation in Zn---12 wt% Al---1 wt% Cu and Zn---27 wt% Al---2 wt% Cu alloys
Rachev, P.; Terziev, L.; Lecomte-Beckers, Jacqueline ULg et al

in Acta Metallurgica et Materialia (1991), 39(9), 2177-2182

In Zn---12 wt% Al---1 wt% Cu and Zn---27 wt% Al---2 wt%Cu alloys aged at 100° and 250°C the precipitation of h.c.p. phases was studied by means of transmission electron microscopy. The presence of the ... [more ▼]

In Zn---12 wt% Al---1 wt% Cu and Zn---27 wt% Al---2 wt%Cu alloys aged at 100° and 250°C the precipitation of h.c.p. phases was studied by means of transmission electron microscopy. The presence of the metastable ηm and ηx-phases was established using the Moiré pattern method. The ηm → η phase transition was observed. Screw dislocations are visualized in (114) with b logical and {220} in η phase precipitates by means of Moiré fringes. [less ▲]

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See detailStudy of composite aluminium alloys produced by stir casting
Lecomte-Beckers, Jacqueline ULg; Coutsouradis, D.; Lamberigts, M.

in Proceedings of the International Conference on Advanced Aluminium and Magnesium Alloys (1990)

Solidification processing of aluminium alloys reinforced by short fibers and particles of SIC was studied. The reinforcements were introduced and dispersed into aluminium alloys melts by the vortex method ... [more ▼]

Solidification processing of aluminium alloys reinforced by short fibers and particles of SIC was studied. The reinforcements were introduced and dispersed into aluminium alloys melts by the vortex method. The paper describes the fabrication process used to provide adequate bonding between reinforcemments and liquid matrix. The commercial alloys (2024, 319) containing element such as Cu or Mg chosen to provide adequate wetting were used and compared. The samples were used in the as-cast state or after hot rolling. The samples were examined both in the as-cast or as-rolled and heat treated conditions (T6). The specimens were submitted to microstructural examinations (optical and SEM) density measurements and mechanical property evaluation. Examinations of the results by statistical analyses show that both SIM chopped fibers and particles increase significantly the mechanical properties of the alloys especially at high temperature. However it is shown that the behaviour of the different alloys is strongly different. The effect reinforcement depends on the nature of the alloy and can be related to microstructural features. [less ▲]

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See detailPhase formation during aging of Zn-12% Al and Zn-27% Al alloys at 100°C.
Terziev, L.; Rachev, P.; Lecomte-Beckers, Jacqueline ULg et al

in Zeitschrift für Metallkunde (1990), 81[6]

The phase formation during ageing of ZrH2 wt% AI and Zna27 wt.% AI alloys at 100 O has been studied by means of transmission electron microscopy and electron diffraction. No formation of ellipsoidal ... [more ▼]

The phase formation during ageing of ZrH2 wt% AI and Zna27 wt.% AI alloys at 100 O has been studied by means of transmission electron microscopy and electron diffraction. No formation of ellipsoidal precipitates of GP 2 and c4 phase bas been observed. Precipitation of hexagonal phases occurs generally on account of the a phase. The <011> habitus plane of a new phase q has been found. The q phase has been distinguished from the metastable Qm using Moire patterns [less ▲]

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See detailSilicon carbide fibers and particles reinforced aluminium alloys produced by stir casting
Lecomte-Beckers, Jacqueline ULg; Coutsouradis, D.; Lamberigts, M.

in Proceedings of The 4th European Conference on Composite Materials - Developments in The Science and Technology of Composite Materials (1990)

This study is concerned with the solidification processing of aluminium alloys reinforced by short fibers and particles of SiC. The reinforcements have been introduced and dispersed into aluminium alloys ... [more ▼]

This study is concerned with the solidification processing of aluminium alloys reinforced by short fibers and particles of SiC. The reinforcements have been introduced and dispersed into aluminium alloys melts by the vortex method. The commercial alloys (2024, 319) containing elements such as Cu or Mg chosen to provide adequate wetting have been used and compared. The samples have been examined both in the as-cast or as-rolled and heat treated conditions (T6). Examinations of the mechanical properties by statistical analyses show that both SiC chopped fibers and particles increase significantly the mechanical properties of the alloys especially at high temperature. [less ▲]

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See detailEtude microstructurale des phases métastables dans les alliages Zn-Al
Lecomte-Beckers, Jacqueline ULg; Terziev, L.; Rashev, P. et al

in Journal de Microscopie et de Spectroscopie Electroniques (1989), 14[2]

Description de la précipitation complexe observée durant le vieillissement des alliages zinc-aluminium avec de petites quantités de cuivre et de magnésium

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See detailQuantitative X-ray microanalysis of precipitates in zinc-aluminium-copper
Rashev, P.; Terziev, Luben; Lecomte-Beckers, Jacqueline ULg et al

in Proceeding of the 12th International Congress on XR optics and microanalyses (1989)

The aim of the present study is to adapt the Cliff-Lorimer method for quantitative analysis of thin foils and to obtain information about the composition of fine metastable precipitates in Zn-Al-Cu alloys ... [more ▼]

The aim of the present study is to adapt the Cliff-Lorimer method for quantitative analysis of thin foils and to obtain information about the composition of fine metastable precipitates in Zn-Al-Cu alloys. The coefficients K(al-zn) and K(al-cu) were determined for accelerating voltage of 200 kV, about which there has no been data ever mentioned. Some applications of the method are given. [less ▲]

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See detailStudy of transition phases during isothermal aging at 250°C of Zn-27% Al alloy
Terziev, L.; Lecomte-Beckers, Jacqueline ULg; Rashev, P. et al

in Physica Status Solidi A : Applied Research (1989), 116[2]

Transition phases during isothermal aging of Zn-27% Al alloy at 250 °C are studied by means of transmission electron microscopy and diffraction technique. The supersaturated f.c.c. phase decomposes into ... [more ▼]

Transition phases during isothermal aging of Zn-27% Al alloy at 250 °C are studied by means of transmission electron microscopy and diffraction technique. The supersaturated f.c.c. phase decomposes into transition phases by formation of GP zones m. Formation of the rhombohedral phases r and of h.c.p. precipitates (m, x) is observed. [less ▲]

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See detailRelation between chemistry, solidification behaviour, microstructure and microporosity in nickel-base superalloys
Lecomte-Beckers, Jacqueline ULg

in Proceedings of 6th International Symposium on Superalloys (1988)

Microporosity formation in nickel-base superalloys is studied experimentally and theoretically. A microporosity index, ΔP*, which depends on solidification parameters and alloy properties has been deduced ... [more ▼]

Microporosity formation in nickel-base superalloys is studied experimentally and theoretically. A microporosity index, ΔP*, which depends on solidification parameters and alloy properties has been deduced. This index can be determined from parameters obtained by quantitative differential thermal analysis. The effect of mean alloying elements on the formation of microporosity is evaluated. Thus, aluminum, titanium and cobalt are found to increase and chromium to decrease microporosity. The effect of carbon depends on aluminum content and can be beneficial or detrimental. [less ▲]

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See detailStudy of microporosity formation in nickel-base superalloys
Lecomte-Beckers, Jacqueline ULg

in Metallurgical Transactions A : Physical Metallurgy and Materials Science (1988), 19A(9)

The susceptibility of nickel-base superalloys to microporosity formation is studied experimentally and theoretically. Analysis of a model introduced herein leads to formulation of a microporosity index ... [more ▼]

The susceptibility of nickel-base superalloys to microporosity formation is studied experimentally and theoretically. Analysis of a model introduced herein leads to formulation of a microporosity index, Ap*, which is expressed in terms of solidification parameters and alloy system properties. This index can be determined from information obtained by quantitative differential thermal analysis. The effect of composition on the formation of microporosity is evaluated. Thus, aluminum, titanium, and cobalt are found to increase, and chromium to decrease microporosity. The effect of carbon is beneficial or detrimental depending on the aluminum content in the alloy. [less ▲]

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See detailStudy of solidification features of nickel-base superalloys in relation with composition
Lecomte-Beckers, Jacqueline ULg

in Metallurgical Transactions A : Physical Metallurgy and Materials Science (1988), 19A(9)

The influence of the six major alloying elements: carbon, chromium, cobalt, molybdenum, titanium, and aluminum on the solidification sequence of nickel-base superalloys was investigated. The ... [more ▼]

The influence of the six major alloying elements: carbon, chromium, cobalt, molybdenum, titanium, and aluminum on the solidification sequence of nickel-base superalloys was investigated. The microstructure was found to depend greatly on aluminum and titanium contents. During solidification the liquid is enriched in titanium and molybdenum, whereas the dendrite cores are richer in cobalt. Aluminum and chromium segregate in the liquid or in the dendrite center, depending on alloy nominal composition. Chemical analysis of the carbides showed that their composition changes during solidification, thus affecting the composition of the residual liquid. The composition of carbides is strongly influenced by titanium and molybdenum nominal content in the alloy. Statistical analysis of the transformation temperatures obtained by DTA showed that titanium and aluminum influence the entire solidification sequence. [less ▲]

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See detailEtude microstructurale des alliages ZA12 et ZA27 au cours du vieillissement
Lecomte-Beckers, Jacqueline ULg; Terziev, L.; Rachev, P. et al

in Journal de Microscopie et de Spectroscopie Electroniques (1988), 13

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See detailMicrostructural study of high strength rolled Zn-Cu-Ti alloys
Lecomte-Beckers, Jacqueline ULg; Walmag, G.

in Micron and Microscopica Acta (1987), 18(3), 241-242

The aim of the research is to define the microstructure required to obtain the better mechanical resistance after rolling of Zn-Cu-Ti alloys which composition range is 0.78-0.98% (in weight)for Cu and 0 ... [more ▼]

The aim of the research is to define the microstructure required to obtain the better mechanical resistance after rolling of Zn-Cu-Ti alloys which composition range is 0.78-0.98% (in weight)for Cu and 0.12-0.18% (in weight) for Ti. These alloys have been rolled at the VM-AF (Vieille-Montagne - Asturienne France) rolling plant [less ▲]

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See detailFonderie de Précision - solidification des métaux et alliages, Notes du cours de "Fonderie de Précision"
Lecomte-Beckers, Jacqueline ULg

Learning material (1987)

I.Metal liquide. Germination. Croissance. Solidification des métaux et alliages monophasés, surfusion de constitution, solidification dendritique. Solidification des métaux et alliages polyphasés ... [more ▼]

I.Metal liquide. Germination. Croissance. Solidification des métaux et alliages monophasés, surfusion de constitution, solidification dendritique. Solidification des métaux et alliages polyphasés, eutectiques. Solidification dirigée, monocristaux. Structure de coulée. Ségrégation : micro et macroségrégation. II. Procédés de coulée : coulée en sable, coulée en carapaces, moulage de précision, coulée en coquille, coulée sous pression, coulée centrifuge, coulée en moules pleins. Défauts de coulée, micro et macroporosités, traitements thermiques des pièces coulées, modélisation de la solidification. III. Visites de fonderies. [less ▲]

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See detailMise en oeuvre de composites à matrice métallique bore-aluminium
Lecomte-Beckers, Jacqueline ULg; Diderrich, E.

in ATB Metallurgie (1987), 27(1), 3-10

Fabrication des composites bore-aluminium par compactage isostatique à chaud et par compression à chaud sur machines MTS. Analyse de leurs propriétés mécaniques. Application à l'industrie aéronautique ... [more ▼]

Fabrication des composites bore-aluminium par compactage isostatique à chaud et par compression à chaud sur machines MTS. Analyse de leurs propriétés mécaniques. Application à l'industrie aéronautique (turbine) [less ▲]

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See detailAspects of the phase transformation during aging of Zn-11% Al and Zn-27% Al alloys
Lecomte-Beckers, Jacqueline ULg; Terziev, L.; Greday, T.

in Proceedings of the International Conference on Phase Transformation (1987)

The purpose of this work is to study the complex evolution observed during aging and the effect of alloying elements in ZA12 and ZA27. The results confirm the existence of the cellular reaction which ... [more ▼]

The purpose of this work is to study the complex evolution observed during aging and the effect of alloying elements in ZA12 and ZA27. The results confirm the existence of the cellular reaction which appears very quickly: after 1 h at 100 deg C the quench alpha sub 1 phase has nearly decomposed and the lamellae have begun to appear. Evidence of the second stage of aging is shown by the aged Zn--10.2% Al which exhibits fine precipitates alpha ' sub m FCC in alpha ' lamellae. When the aging time is increased diffusion of Zn inside these particles increases the difference in crystalline parameters leading to alpha ' HCP precipitates and finally to eta HCP. The aging is completed when the fine microstructure alpha ' sub m has disappeared leading is large globular grains of alpha and Beta [less ▲]

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See detailMicrostructural study of Zn-Al alloy
Terziev, L.; Rashev, P.; Lecomte-Beckers, Jacqueline ULg et al

in Proceedings of The 4th Physics and Chemistry of Solids, School-Symposium Physics of Metals, Polish Academy of Sciences, Institute for Low Temperature and Structure Research (1987)

It is well known that zinc-aluminium alloys posses very good mechanical properties. This is the reason why the investigation of their ageing characteristics is very important for the practice. Several ... [more ▼]

It is well known that zinc-aluminium alloys posses very good mechanical properties. This is the reason why the investigation of their ageing characteristics is very important for the practice. Several solid state reactions between alpha, beta, epsilon and T phases have been established for such materials alloyed with copper, but there has been no detailed on the formation, development and transformation of metastable phases into stable ones. This is exactly the aim of our investigation. [less ▲]

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See detailMicrostructural study of Zn-11% Al and Zn-27% Al alloys
Lecomte-Beckers, Jacqueline ULg; Terziev, L.; Wegria, J. et al

in Proceedings of the 25th Annual Conference of Metallurgists (1986)

Zinc-aluminium alloys with small amounts of copper and magneisum (ZA alloys) are used in a number of casting processes. They offer the foundry industry a family of zinc alloys with a wide range of ... [more ▼]

Zinc-aluminium alloys with small amounts of copper and magneisum (ZA alloys) are used in a number of casting processes. They offer the foundry industry a family of zinc alloys with a wide range of mechanical properties able to meet a large spectrum of performance criteria. However promising the characteristics of these alloys, microstructural studies of them are incomplete. It has been shown that copper additions to ZA alloys modify the number of the phase existing in the binary zinc-aluminium system as well as their transformation kinetics. Microstructural studies have shown not only the heterogeneity of the microstructure but also the presence of a zinc-rich metastable phase and the evolution of the composition of the ternary phase Zn-Al-Cu (T) during ageing. This situation is not surprising as several studies have shown the existence of metastable phases in the binary system Al-Zn with high aluminium content. the complexity of the microstructure leads us to search further for a better understanding of the binary Zn-Al alloys, with Al contents corresponding to ZA 12 and ZA 27 wihout any Cu and Mg, in order to precise about the complex evolution to stable phases observed in these alloys. [less ▲]

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