Structural and thermodynamic properties of elemental and bimetallic nanoclusters: an atomic scale study

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An Atomistic Study of Mechanical Deformation of nanostructured Ni³Al synthesized by cluster compaction

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Atomic scale modelling of nanosize Ni3Al cluster beam deposition on Al, Ni and Ni3Al (111) surfaces

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Atomic-scale modeling of cluster-assembled NixAl1-x thin films

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Stress distribution and mechanical properties of free and assembled Ni³Al nanoclusters

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Atomic-scale modeling of cluster-assembled (formula presented) thin films

Thermodynamic and structural properties of Ni-Al cluster assembled materials are investigated at the atomic scale. Model predictions are available for elemental systems but the field of bimetallic nanostructured systems remains close to unexplored. The aim of the present work is to model at the atomic scale the structural and segregation properties in the (formula presented) bimetallic cluster assembled materials that are synthesized in two different ways. In the first, isolated clusters are compacted at high pressure. We consider the (formula presented) and (formula presented) phases of the initial free clusters. Compaction of clusters at thermodynamic equilibrium is modeled by classical molecular dynamics combining isobaric and isothermal schemes. After compaction, interface segregation is computed by Metropolis Monte Carlo importance sampling in the semigrand canonical ensemble. After this model treatment, clusters are found to keep their identity, and their structural and segregation states do not differ much from those in the initial free clusters. The cluster cores keep the stable bulk phases while segregation may take place at the interfaces. The second method is low-energy cluster beam deposition. Cluster impact is found to influence chemical and structural order in the films formed. This is shown and discussed on the example of (formula presented) cluster deposition. Molecular dynamics is used therefore, which accounts for electron-phonon coupling in the equations of motion. The slowing down of a single cluster is examined in detail. It is found that the expitaxial accommodation of the cluster with the substrate and chemical order in the cluster depend on the mechanical properties of the substrate material. Competition between chemical order and epitaxy is observed. The harder the material, the higher the epitaxy and the lower the chemical order. The cluster impact induces significant chemical disorder but the clusters forming the cluster assembled film keep their initial identities. Similarly to the sample obtained by compaction, this one displays partial structural and chemical order at its interfaces. The film density is particularly low and the open volumes form a fully interconnected network of pores. © 2002 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Nanoscale alloys and core-shell materials: Model predictions of the nanostructure and mechanical properties

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Determination of the phase diagram from interatomic potentials: The iron-chromium case

Prior to applying any interatomic potential, it is important to know the stability of the different phases it describes. In the literature many methods to determine the phase diagram from an interatomic potential are described. Although for pure elements the procedure to obtain the thermodynamic functions is well established, for alloys it is not. In this work a method is developed to determine the phase diagram, i.e. solubility limits and spinodal gap, for the case of miscibility gaps. The method combines Monte Carlo simulations in the isobaric semi-grand canonical ensemble, full thermodynamic integration and Redlich-Kister expansions to parameterize the Gibbs free energy. Besides numerical inaccuracies, this method does not rely on any physical approximations to determine the phase diagram of a given interatomic potential. The method is applied to two different Fe-Cr potentials that are widely used in the literature. The resulting phase diagrams are discussed by comparing them to the experimental one and ones obtained in other works from the same potentials. © 2011 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Metropolis Monte-Carlo simulation of segregation in Fe–Cr alloys

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