Model predictions and experimental characterization of Co-Pt alloy clusters

Moskovkin, Pavel; Pisov, Stoyan; Hou, Marc; Raufast, Cécile; Tournus, Florent; Favre, Luc; Dupuis, V.

doi:10.1140/epjd/e2007-00066-0

Cited by 20 publications

(19 citation statements)

References 23 publications

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“…77 Nevertheless, we consider the obtained cluster expansion to be reliable for qualitative estimation of configurational effects within the most technologically interesting region of low/medium temperatures. In other theoretical simulations of Co-Pt, 25,26,[78][79][80][81][82] the predicted bulk order-disorder transition temperatures are substantially lower than those measured experimentally.…”

Section: Bulk Equiatomic Cluster Expansionmentioning

confidence: 59%

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Tuning ofL10atomic order in Co-Pt nanoparticles:Ab initioinsights

Chepulskii

Butler

2012

Phys. Rev. B

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Monte Carlo simulation of the atomic configurational behavior of Co-Pt nanoparticles is performed in wide temperature-composition-size ranges. The simulation is based on bulk and local (inhomogeneous) cluster expansions calculated from first principles. A sharp drop of equilibrium L1 0 order is predicted for small equiatomic particles at low temperatures. This drop is explained by the interplay of two effects. First, the strong Pt and Co segregation to the first and second surface layers, respectively (core/Co/Pt or "onion2shell" profile) cause a depletion of Pt atoms within the core of small Co-Pt particles. Second, L1 0 is an adaptive structure on the fcc-restricted ground-state phase diagram of Co-Pt. Nevertheless, we show that a remarkable degree of L1 0 order can be restored by tuning the total composition of small Co-Pt particles.

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Section: Bulk Equiatomic Cluster Expansionmentioning

confidence: 59%

“…25 and 26 can be explained by a sensitivity of segregation tendencies to the choice of atomic potential. 80,81 A stronger Pt surface segregation in Co-Pt than in Fe-Pt may be attributed to a larger difference in atomic radii between Pt and Co than Pt and Fe. Table IV.…”

Section: Surface Potentialmentioning

confidence: 99%

Tuning ofL10atomic order in Co-Pt nanoparticles:Ab initioinsights

Chepulskii

Butler

2012

Phys. Rev. B

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“…A previous study showed that interfaces in similar nanostructured materials display some similarities with liquids [4,5] and this suggests the relevance of low friction forces between grains in plastic deformations as well. The further identification of the atomic scale deformation mechanisms is in progress.…”

Section: Resultsmentioning

confidence: 85%

“…If the NsM is formed by grains with sizes smaller than about 10 nm, no dislocation activity is expected [3] and the role of interfaces and interface junctions in mechanical properties may become dominant. Interfacial diffusion is predicted very high and diffusion coefficients were predicted as high as in a liquid [4,5]. Several mechanisms of deformation (like GB sliding, grain rotation, interfacial viscosity, etc.)…”

Section: Introductionmentioning

confidence: 99%

An atomistic study of mechanical deformation of nanostructured Ni3Al synthesized by cluster compaction

Журкин

Hou

2007

Journal of Alloys and Compounds

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“…This way, an infinite nanostructured material is modeled. The procedure was already used for studying interfacial atomic diffusion properties 55 and was found to be satisfactory, despite the artificial planar interface generated by the boundary conditions. In addition, pressure and shear distributions perpendicular to the slab indicate no significant modification of the stress at the artificial interface created by the boundary condition applied.…”

Section: Equilibrium Propertiesmentioning

confidence: 99%

Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

2006

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Classical molecular dynamics with a semiempirical N-body potential is used to study the distribution of local stress in bimetallic Ni 3 Al nanoparticles and in cluster-assembled materials. The materials considered are synthesized with these particles by low-energy deposition at 0.5 eV per atom and by compaction with an external pressure of 2 GPa, thus featuring different nanostructures. Both are nanoporous, the lowest density being obtained by deposition. Their mechanical response to a uniaxial external load is then studied and deformation mechanisms are identified and are found to be similar in both nanostructures. In the core of isolated clusters, the partial pressures on the nickel and aluminium subsystems are found to differ by several GPa and, as a balance to surface tension, the hydrostatic core pressure is positive and depends on the cluster size. The surface stress is tensile and, because of structural disorder, the partial pressures distributions on Ni and Al at the surface are scattered. When nanostructured systems are formed, strong and highly inhomogeneous shear stress appears, the cluster cores may become tensile, and the interfacial areas remain mainly tensile as well. The partial pressure difference between Ni and Al is somewhat reduced. It is shown that the effect of temperature is to reduce this difference still further and to homogenize the spatial stress distribution. When subjected to a uniaxial stress, both materials display an elastic and a plastic regime. The elastic limit is the lowest for the most porous material and decreases with increasing temperature. Plastic deformation is dominated by both grain boundary sliding and by the enlargement of the open volumes, without evidence for the nucleation of cracks. These open volumes are found to facilitate dislocation activity which is evidenced in grains with sizes as small as two nanometers. This dislocation activity is found to result in the production of stacking faults as well as to the recovery of defects induced by the deposition or by the compaction.

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Model predictions and experimental characterization of Co-Pt alloy clusters

Cited by 20 publications

References 23 publications

Tuning ofL10atomic order in Co-Pt nanoparticles:Ab initioinsights

Tuning ofL10atomic order in Co-Pt nanoparticles:Ab initioinsights

An atomistic study of mechanical deformation of nanostructured Ni3Al synthesized by cluster compaction

Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

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