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Type 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
  Publication Intermixing and phase separation at the atomic scale in Co-rich (Co,Fe) and Cu multilayered nanostructures Volume Journal Article
Pages 2005
  Abstract Applied Physics Letters  
  Corporate Author Appl. Phys. Lett.  
Publisher 87  
Editor
  Summary Language 121912:1-3 Series Editor LEAP  
Abbreviated Series Title 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.
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no NU @ karnesky @ 420
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Mao, Zugang; Booth-Morrison, Christopher; Sudbrack, Chantal K.; Martin, Georges; Seidman, David N. Kinetic pathways for phase separation: An atomic-scale study in Ni–Al–Cr alloys Journal Article 2011 Acta Materialia 60 4 1871-1888 Nickel-based superalloys; Kinetic pathways; Atom probe tomography; Lattice kinetic Monte Carlo; Nanostructures The kinetic pathways involved in the formation of [gamma]'(L12 structure)-precipitates during aging of concentrated Ni–Al–Cr alloys at 873 K, for three distinct alloy compositions, are studied experimentally by atom probe tomography, and computationally with lattice kinetic Monte Carlo (LKMC) simulations using parameters deduced from first-principles calculations of cohesive energies, and from experimental diffusion data. It is found that the compositional evolution of the [gamma]'-precipitate phase does not follow the predictions of a classical mean-field model for coarsening of precipitates in ternary alloys. LKMC simulations reveal that long-range vacancy–solute binding plays a key role during the early stages of [gamma]'-precipitation. With the aid of Monte Carlo techniques using the parameters employed in the LKMC simulations, we compute the diffusion matrix in the terminal solid-solutions and demonstrate that key features of the observed kinetic pathways are the result of kinetic couplings among the diffusional fluxes. The latter are controlled by the long-range vacancy–solute binding energies. It is concluded that, because it neglects flux couplings, the classical mean-field approach to phase separation for a ternary alloy, despite its many qualitatively correct predictions, fails to describe quantitatively the true kinetic pathways that lead to phase separation in concentrated metallic alloys. 1359-6454 no NU @ karnesky @ 11306
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Mao, Zugang; Sudbrack, Chantal K.; Yoon, Kevin E.; Martin, Georges; Seidman, David N. The mechanism of morphogenesis in a phase separating concentrated multi-component alloy Journal Article 2007 Nature Materials 6 3 210-216 What determines the morphology of a decomposing alloy? Besides the well established effect of the nucleation barrier, we demonstrate that, in a concentrated multi-component Ni(Al,Cr) alloy, the details of the diffusion mechanism affect strongly the kinetic pathway of precipitation. Our argument is based on the combined use of atomic-scale observations, employing 3-dimensional atom-probe tomography (3-D APT), lattice kinetic Monte Carlo simulations, and the theory of diffusion. By an optimized choice of thermodynamic and kinetic parameters we first reproduce the 3-D APT observations, in particular the early stage transient occurrence of coagulated precipitates. We then modify the kinetic correlations among the atomic fluxes in the simulation, without altering the thermodynamic driving force for phase separation, by changing the vacancy-solute interactions, resulting in a suppression of coagulation. Such changes can only be quantitatively accounted for with nonzero values for the off-diagonal terms of the Onsager matrix, at variance with classical models. no NU @ karnesky @ 1885
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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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Martin, A.; Block, J. A field ion source with electrical mass filter Journal Article 1973 Messtechnik 81 field desorption; Field Evaporation no 6619
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Martin, C.; Blavette, D.; Sarrau, J. M. Performance of a time-of-flight atom probe Journal Article 1984 Rev. Phys. Appl. 19 atom probe field ion microscopy no 8604
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Martin, G. Reconciling the Classical Nucleation Theory and Atomic Scale Observations and Modeling Journal Article 2006 Advanced Engineering Materials 8 12 1231-1236 Cast iron • Fatigue • Graphite No abstract. 1527-2648 no NU @ karnesky @ Martin2006 1859
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Martin, G. The Joint Research Program ?CPR Precipitation?: - Breakthroughs in the Understanding of Kinetic Pathways for the Early Stages of Phase Separation Journal Article 2006 Advanced Engineering Materials The Joint Research Program ?CPR Precipitation? 8 12 1222-1224 No abstract. 1527-2648 no NU @ karnesky @ Martin2006 1854
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Martin, G. A diffuse interface model for the interfacial transfer coefficient Journal Article 2005 Acta Materialia 53 9 2629-2632 Diffusion; Interfaces; Alloys; Kinetics; Phase field models; Theory Based on an extension to non-equilibrium problems, of Cahn's interface layer thermodynamics, we demonstrate that the matrix of transfer coefficients across a coherent interface between two phases, [alpha] and [beta], can be viewed as a correction to the Onsager's matrix of mobility coefficients along the continuous concentration profile. The latter coefficients are defined along the equilibrium concentration profile in the interfacial layer and in the [alpha]- and [beta]-phases. Combining the above definition with that of solute interfacial excess, we can define transfer coefficients relative to two components chosen arbitrarily, the values of which are intrinsic properties of the interfacial layer, independent of its precise location and thickness. no NU @ p-kolli @ 9702
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Martin, Georges Curriculum Vitae Georges Martin Miscellaneous 2021 2021 Curriculum Vitae Georges Martin no NU @ isheim @ 11562
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