A. Coujou

Centre d’Élaboration de Matériaux et d’Études Structurales

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N. Clément

Centre d’Élaboration de Matériaux et d’Études Structurales

Florence Pettinari‐Sturmel

Centre d’Élaboration de Matériaux et d’Études Structurales

Alain Couret

Centre d’Élaboration de Matériaux et d’Études Structurales

Pierre Caron

Office National d'Études et de Recherches Aérospatiales

Mustafa Benyoucef

Cadi Ayyad University

J. Douin

Centre d’Élaboration de Matériaux et d’Études Structurales

F. Pettinari

Centre d’Élaboration de Matériaux et d’Études Structurales

D. Caillard

Centre d’Élaboration de Matériaux et d’Études Structurales

Marie‐José Casanove

Centre d’Élaboration de Matériaux et d’Études Structurales

P. Lours

Université Toulouse III - Paul Sabatier

Cooperative Institutions

Centre National de la Recherche Scientifique

Université Toulouse III - Paul Sabatier

Centre d’Élaboration de Matériaux et d’Études Structurales

Université de Toulouse

Université de Poitiers

Office National d'Études et de Recherches Aérospatiales

Institut Pprime

IMT Mines Albi

École Nationale Supérieure de Mécanique et d'Aérotechnique

Laboratoire d'Optique Appliquée

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Role of the y/y' Interface on the Mechanical Properties of Single Crystals Nickel Base Superalloys

Diffusion and defect data, solid state data. Part B, Solid state phenomena/Solid state phenomena (1998)

A. Coujou Mustafa Benyoucef M. Legros N. Clément

Interface (matter)

Base (topology)

10.4028/www.scientific.net/ssp.59-60.185

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Citations (7)

Local disordering and reordering phenomena induced by mobile dislocations in short-range-ordered solid solutions

Philosophical Magazine A (2002)

Florence Pettinari‐Sturmel Mustapha Jouiad H. O. K. Kirchner N. Clément A. Coujou

Abstract Dislocation motion in short-range-ordered solid solutions under stress are investigated in situ by transmission electron microscopy. For the first time, local reordering created by the back slip of mobile dislocations is proven to exist. Dislocation movement within pile-ups produces local disordering by forward slip during loading, and local reordering by back slip during unloading. Within a pile-up, the driving force for this mechanism is the diffuse antiphase-boundary energy created by the movement of the leading dislocation.

10.1080/01418610208239633

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Citations (16)

Characterisation of short-range order using dislocations

Zeitschrift für Metallkunde (2006)

Florence Pettinari‐Sturmel J. Douin A. Coujou N. Clément

Abstract The mobile dislocation pile-ups observed during in situ straining experiments have been used as probes to describe the short-range order (SRO) present in the phase of nickel-base superalloys. An experimental approach, based on the measurement of the dislocation positions, to characterise the SRO has been developed. This paper focuses on the main results we have obtained on this topic. A quantitative analysis allows to get the chemical forces associated with SRO, and also the SRO degree. For the first time, the energies associated with SRO are evaluated along a dislocation pile-up as a function of temperature. More generally, a description of the SRO is proposed: SRO is seen as a heterogeneous distribution at the micrometer scale of nanometric areas. Another characteristic has been evidenced: the reversible character of the SRO creation.

Short range order

10.3139/146.101243

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Citations (16)

Stacking‐fault energy at room temperature of the γ matrix of the MC2 Ni‐based superalloy

Philosophical Magazine A (1995)

Mustafa Benyoucef B. Décamps A. Coujou N. Clément

Abstract The γ-phase of the MC2 Ni-based superalloy has been characterized using both in situ experiments and post-mortem observations (bright field and weak beam) in transmission electron microscopes. A mean value of the stacking-fault energy (about 31 mJ m−2) has been obtained through the measurement of dissociated nodes and of the dissociated width of dislocations. Furthermore, the plastic deformation has been shown to be controlled by the collective movement of dense pile-ups, and the existence of a local order has been deduced.

Stacking-fault energy

Stacking fault

Matrix (chemical analysis)

10.1080/01418619508236228

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Citations (40)

Deceleration of relaxation in a CuSi alloy

Scripta Metallurgica (1983)

A. Coujou Pierre Coulomb

10.1016/0036-9748(83)90337-x

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Citations (6)

Quantitative analysis of dislocation pile-ups in thin foils compared to bulk

Materials Science and Engineering A (2004)

Florence Pettinari‐Sturmel G. Saada J. Douin A. Coujou N. Clément

Stress relaxation

10.1016/j.msea.2004.05.048

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Citations (9)

Dynamic of screw superlattice dislocations in a γ l12 structure. In situ observation at high temperature

Revue de Physique Appliquée (1988)

N. Clément D. Caillard A. Bénéteau A. Coujou

10.1051/rphysap:01988002304067500

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Some Deformation Micromechanisms in Ni-Based Superalloys Evidenced Using TEM <i>In Situ</i> Experiments

Advanced materials research (2011)

Florence Pettinari‐Sturmel Mustafa Benyoucef J. Douin Pierre Caron Didier Locq

In situ straining of microsamples have been carried out at different temperatures in a transmission electron microscope (TEM) to provide information about the elementary micromechanisms, which control the deformation in Ni-based superalloys at the nano and microscopic scales. The obstacles to the propagation of the dislocations have been identified and quantified when possible. The strengthening effect in the -matrix channels and the shearing of ' precipitates have been chosen to illustrate some results deduced from moving dislocation analysis. A quantitative evaluation of the stresses acting on dislocations has been performed. The shearing process of the ' precipitates at 850°C has been precisely analysed.

Shearing (physics)

10.4028/www.scientific.net/amr.278.90

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A new TEM method for the characterization of the tertiaryγ′ nano-precipitates in a PM disk superalloy: influence of ageing

The Philosophical Magazine A Journal of Theoretical Experimental and Applied Physics (2006)

S. Raujol Florence Pettinari‐Sturmel J. Douin N. Clément A. Coujou

Abstract An original method for characterizing the γ′-phase tertiary precipitates in a Ni-based superalloy manufactured by powder metallurgy is described. This investigation is made using post mortem transmission electron microscopy (TEM). It is based on the analysis of sheared areas within crept specimens, which allows the precipitates revealed by the dislocations in their glide plane to be observed. The characteristics of these nano-precipitates, i.e. their size, their volume fraction and the channel width between them, are determined for two different heat treatments (HTs). The results show a wide distribution of the microstructural parameters for a given HT, but only slight differences between the microstructures produced by the two different HTs. This microstructural information allows a better understanding of the wide variety of the deformation micromechanisms observed during creep at high temperature. Acknowledgments We are grateful for financial support from le Ministère de la Recherche, le Ministère de l'Equipement, des Transports et du Logement (programme RRIT "Recherche aéronautique sur le supersonique").

Volume fraction

Characterization

10.1080/14786430600740658

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Citations (4)

850°Cにおけるラフト化γ/γ′超合金の変形の微視機構のその場観察

Materials Science and Engineering A (2002)

M Legros Nathalie Lise Clément Pierre Caron A. Coujou

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