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Type Martin, Georges
  Publication Solute Transfer at Interfaces Volume Manuscript
Pages 2003
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no NU @ karnesky @ 103
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Mao, Zugang; Sudbrack, Chantal K.; Yoon, Kevin E.; Martin, Georges; Seidman, David N. Impact of vacancy diffusion on the early decomposition stages of alloys Journal Article 2005 Nature To be submitted 36 The kinetic pathway for nucleation and growth is commonly thought to be dictated by the initial supersaturation of solutes in the solid solution undergoing phase separation. We demonstrate that the details of the diffusion mechanism, in the solid solution affect deeply the early stage morphologies of precipitates. Our argument is based on a combined use of atomic-scale observations, with atom-probe tomography (APT) and lattice kinetic Monte Carlo simulation of a Ni(Al,Cr) alloy. By an optimized choice of thermodynamic and kinetic parameters we first reproduce the experimental APT observations. We then modify only the long-range vacancy-solute binding energy, without altering the thermodynamic driving force for phase separation, thereby demonstrating that the microstructural evolution changes from a coagulation to an evaporation-condensation coalescence mechanism. The changes can only be accounted for with nonzero values for the vacancychemical potential and off-diagonal terms of the Onsager matrix, at variance with classical models. no NU @ karnesky @ 163
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Clouet, Emmanuel; Nastar, Maylise; Barbu, Alain; Sigli, Cristophe; Martin, Geroges Precipitation in Al-Zr-Sc alloys:a comparison between kinetic Monte Carlo, cluster dynamics and classical nucleation theory Book Chapter 2005 Solid-Solid Phase Transformations in Inorganic Materials 2 683-703 Zr and Sc precipitate in aluminum alloys to form the Al3ZrxSc1−x compound which, for low supersaturations of the solid solution, exhibits the L12 structure. The aim of the present study is to model at an atomic scale the kinetics of precipitation and to build mesoscopic models so as to extend the range of supersaturations and annealing times that can be simulated up to values of practical interest. In this purpose, we use some ab initio calculations and experimental data to fit an Ising type model describing thermodynamics of the Al-Zr-Sc system. Kinetics of precipitation are studied with a kinetic Monte Carlo algorithm based on an atom-vacancy exchange mechanism. Cluster dynamics is then used to model at a mesoscopic scale all the different stages of homogeneous precipitation in the two binary Al-Zr and Al-Sc alloys. This technique correctly manages to reproduce both the kinetics of precipitation simulated with kinetic Monte Carlo as well as experimental observations. Focusing on the nucleation stage, it is shown that classical theory well applies as long as the short range order tendency of the system is considered. This allows us to propose an extension of classical nucleation theory for the ternary Al-Zr-Sc alloy. TMS Howe, J. M.; Laughlin, D. E.; Lee, J. K.; Dahmen, U.; Soffa, W. A. no NU @ karnesky @ 166
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Deconihout, B.; Saint-Martin, R.; Jamot, C.; Bostel, A. Improvement of the mass resolution of the atom probe using a dual counter-electrode Journal Article 2003 Ultramicroscopy 95 239-249 no 9199
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Menand, A.; Martin, C.; Sarrau, J. M. Field evaporation charge state of boron ions: a temperature effect study Journal Article 1984 Journal de Physique J. de Phys. 45-C9 no 8612
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Soisson, F.; Martin, G. Kinetics of Decomposition of Metastable Solid Solutions: Comparison between Monte Carlo Simulations and Classical Theories Book Chapter 1999 Proceedings of the International Conference on Solid-Solid Phase Transformations 757-760 precipitation, nucleation, incubation time, Monte Carlo simulations We present a study on the kinetics of coherent precipitation in metallic binary alloys by . ~ Monte ~ & l osim ulations, based on a simple atomistic model with diffusion by vacancy jumps~ . The whole precipitation process (from early stages to late stage coarsening) is followed for various surpersaturations and temperatures, and typical behaviours observed in the simulations are compared to those predicted by the classical theories. Special emphasis is placed on the first stages of the decomposition (incubation and nucleation). no NU @ karnesky @ 276
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Athenes, M.; Soisson, F.; Bellon, P.; Martin, G. Solid State Diffusion and Configurational Kinetics Book Chapter 1999 Proceedings of the International Conference on Solid-Solid Phase Transformations 433-440 precipitation, ordering, nucleation, growth, coarsening, diffusion, vacancy, atomic scale, Monte Carlo simulation, kinetics no NU @ karnesky @ 277
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Ladwig, Peter F.; Olson, Jesse D.; Bunton, Joseph H.; Larson, David J.; Ulfig, Robert M.; Martens, Richard L.; Gribb, Tye T.; Kelly, Thomas F.; Bonsager, Martin C.; Schultz, Allan E.; Pant, Bharat B.; Chang, Y. Austin Intermixing and phase separation at the atomic scale in Co-rich (Co,Fe) and Cu multilayered nanostructures Journal Article 2005 Applied Physics Letters Appl. Phys. Lett. 87 121912:1-3 LEAP Despite the fact that Co-rich (Co,Fe) alloys and Cu are immiscible materials in bulk form, evidence of thermally induced mixing at the atomic scale has been observed in thin-film multilayers of (Co,Fe) and Cu. However, long term anneals at lower temperatures produced a breakup of the multilayers into a two-phase mixture of (Co,Fe) and Cu particles. The observations were made with the use of the three-dimensional atom probe technique, with supporting evidence from differential scanning calorimetry and x-ray diffraction. Besides their scientific importance, these results are of interest where these (Co,Fe) and Cu thin films are used to produce the giant magnetoresistive effect. no NU @ karnesky @ 420
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Antepara, I.; Villarreal, I.; Rodriguez-Martinez, L.M.; Lecanda, N.; Castro, U.; Laresgoiti, A Evaluation of ferritic steels for use as interconnects and porous metal supports in IT-SOFCs Journal Article 2005 Journal of Power Sources 151 103-107 SOFC; ferritic stainless steel; oxidation; ASR As a way of reducing the production costs of stacks by replacing ceramic components with metal components with a similar thermal expansion coefficient (TEC), today, much of the research work has focused on SOFCs operating at temperatures of under 800 degrees C. Some semi-commercial ferritic stainless steels (FSS) satisfy this TEC. Ikerlan has evaluated samples of two of these. Also, AMETEK stainless steel powders were tested in sintered disks until they were completely densified in order to compare results from dense and porous materials. The first tests performed by Ikerlan were conducted with dense samples and included the oxidation test in air at 800 degrees C and measurements of contact surface electrical resistance (area specific resistance, ASR), to compare electrochemical techniques (electrochemical impedance spectroscopy, EIS) with the traditional four-wire method and indirect measuring of the resistance through current and voltage measurements. An alloy from the last melt manufactured by the company ThyssenKrupp VDM GmbH performed best. These results did not differ greatly from the previous laboratory results attained during alloy development. Only AMETEK powder metallurgy materials were tested as porous bodies, to compare these with these dense materials. and were found to provide much higher oxidation levels, as might be expected. While dense materials can operate under the working conditions of the SOFC, porous materials still need new alloys. no NU @ karnesky @ 497
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Habibi-Bajguirani, H. R.; Martin, J. W.; Cantor, B. TEM Studies of the Precipitation in High {Zr} Spray Formed {Al-Li-Zr} Book Chapter 1996 Aluminium Alloys: Their Physical and Mechanical Properties, Pts 1-3 217 871-876 Materials Science Forum refbase @ user 1166
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