References of "Lecomte-Beckers, Jacqueline"
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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 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 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 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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See detailMicroporosity formation in nickel-base superalloys in relation to their solidification sequence
Lecomte-Beckers, Jacqueline ULg; Lamberigts, M.

in Proceedings of the International Conference of High Temperature Alloys for Gas Turbine and Other Applications (1986)

This work is aimed at showing how the proneness of superalloys to microporosity formation can be estimated by the tsP* pararneter which makes use of various solidification features. The latter can be ... [more ▼]

This work is aimed at showing how the proneness of superalloys to microporosity formation can be estimated by the tsP* pararneter which makes use of various solidification features. The latter can be derived from quantitative differential thermal analysis (DTA) resuits through the original method described in the text. The technique was applied to two IN 100 master meUs of distinct grades (virgin or revert) which had been showrt to behave very differently in the foundry. It led to ascribe the poorer performance of the revert meit to its particular solidification sequence leading higher dendrite tortuosity and lesser residual liquid fluidity. [less ▲]

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See detailReverting foundry nickel-base superalloys
Lamberigts, M.; Lecomte-Beckers, Jacqueline ULg; Drapier, J.-M.

in International Conference on High Temperature Alloys for Gas Turbine and Other Applications (1986)

This work was part of a COST 50 project aimed at ways to make revert IN 100 less prone to soundness defects and associated property degradations. It was based on carrots cast from 5 master distinct master ... [more ▼]

This work was part of a COST 50 project aimed at ways to make revert IN 100 less prone to soundness defects and associated property degradations. It was based on carrots cast from 5 master distinct master melts, which were evaluated through metallography and Differential Thermal Analysis. Recycling was shown to affect grain size and morphology, carbide precipitation features, eutectic pool distribution and above all, microporosity level. The experimental evidence strongly suggests that, in revert master melts, carbides grow onto pre—existent nuclei made of TiN. This in turn reduces total heat of solidification, thus making the residual liquid substantially less fluid and consequently less capable of coxnpensating for solidification shrinkage in a dendrite structure which is more “tortuous”, because of its lower maturation rates. The effects of recycling can therefore be better accounted for in terms of bound nitrogen rather than of gas content as such. [less ▲]

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See detailThe investment casting and processing of cobalt-base and cobalt-bearing superalloys
Lamberigts, M.; Lecomte-Beckers, Jacqueline ULg; Walmag, G. et al

in Second Congress Cobalt Metallurgy and Uses (1985)

To cope with the demands of engine manufacturers and other users, superalloys have been brought to work in service at temperatures which represent a very substantial fraction of their melting point. In ... [more ▼]

To cope with the demands of engine manufacturers and other users, superalloys have been brought to work in service at temperatures which represent a very substantial fraction of their melting point. In addition to high temperature capability, they must exhibit mechanical strength, not only under static, but also under cyclic stressing conditions, and offer appropriate oxidation and corrosion resistance. This can only be achieved by tailoring their chemistry and processing conditions to the particular needs of the application under consideration. The evolution of component design and alloy chemistry, and some compositional effects and processing improvements in cast Ni-base superalloys are discussed. [less ▲]

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See detailLes matériaux composites à matrice métallique
Lecomte-Beckers, Jacqueline ULg

Learning material (1985)

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