Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe

Tanimoto, H.; Pasquini, Luca; Prümmer, R.; Kronmüller, H.; Schaefer, H.‐E.

doi:10.1016/s1359-6462(00)00326-2

Cited by 27 publications

(19 citation statements)

References 20 publications

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“…The activation energy found for tracer diffusivity in the high-density n-metals is almost the same as that reported for the GB diffusion in the p-metals. [10][11][12] A steep increase in the internal friction, Q À1 , of n-metals is observed at the temperature slightly higher than 300 K, where the activation energy estimated is also close to that reported for the GB diffusion in p-metals. [13][14][15][16][17][18][19][20] These results indicate that intrinsic natures of the GB regions in n-metals appear to be similar to those in p-metals.…”

Section: Introductionsupporting

confidence: 81%

Anelasticity Study on Motions of Atoms in the Grain Boundary Regions in Nanocrystalline Gold

2003

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High-density nanocrystalline (n-) Au was prepared by the gas deposition method. Various anelastic and plastic creep processes associated with the grain boundary (GB) regions were observed. The vibrating reed measurements at 10 2 Hz with strain amplitude of 10 À6 show a very broad internal friction peak near 95 K, Q À1 p,95 K , and a steep increase in the anelastic strain above 200 K, " a-I,>200 K . The tensile tests show a steep increase in the anelastic strain above 200 K, " a-II,>200 K , for the stress beyond a few MPa and a linear plastic creep strain above 200 K, " pc-1 , for stress range between 30 MPa and 150 MPa. The activation parameters, 1= 0 of 3 Â 10 11 s À1 and E of 0.16 eV, are found for Q À1 p,95 K , where 0 and E are a pre-exponential factor and an activation energy of the relaxation time . We surmise that simple relaxation processes are responsible for Q À1 p,95 K . The values of 1= 0 and E found for " a-I,>200 K and " a-II,>200 K decrease with increasing the applied stress or the temperature, indicating that their atomic processes are the same feather. Further, E found for " pc-1 is similar to or slightly smaller than that of " a-II,>200 K . These observations indicate that the atomic motions in the GB regions of n-Au develop in scale in the order of the underlying processes for " a-I,>200 K , " a-II,>200 K and " pc-1 , and are so different from those in the conventional polycrystalline Au.

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Section: Introductionsupporting

confidence: 81%

Anelasticity Study on Motions of Atoms in the Grain Boundary Regions in Nanocrystalline Gold

2003

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“…From experimental results and theoretical models it follows that the highly enhanced diffusion kinetics in nc materials is related to the much increased portions of grain boundaries (GBs) and triple junctions (TJs) [9][10][11][12][13][14][15][16][17]. The GBs in nc materials by SPD are in high-energy, non-equilibrium states, making them the rapid diffusion paths [7,10].…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution and formation of nanocrystalline intermetallic compound during surface mechanical attrition treatment of cobalt

Tao

Wei

et al. 2007

Acta Materialia

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Nanocrystalline intermetallic Co 3 Fe 7 was produced on the surface of cobalt via surface mechanical attrition (SMA). Deformationinduced diffusion entailed the formation of a series of solid solutions. Phase transitions occurred depending on the atomic fraction of Fe in the surface solid solutions: from hexagonal close-packed (<4% Fe) to face-centered cubic (fcc) (4-11% Fe), and from fcc to body-centered cubic (>11% Fe). Nanoscale compositional probing suggested significantly higher Fe contents at grain boundaries and triple junctions than grain interiors. Short-circuit diffusion along grain boundaries and triple junctions dominate in the nanocrystalline intermetallic compound. Stacking faults contribute significantly to diffusion. Diffusion enhancement due to high-rate deformation in SMA was analyzed by regarding dislocations as solute-pumping channels, and the creation of excess vacancies. Non-equilibrium, atomic level alloying can then be ascribed to deformation-induced intermixing of constituent species. The formation mechanism of nanocrystalline intermetallic grains on the SMA surface can be thought of as a consequence of numerous nucleation events and limited growth.

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“…This is related to that the diffusion-controlled grain boundary processes play an important, sometimes dominant part in the development of plastic deformation, structural degradation, and destruction of metal polycrystals [3]. A rather great body of theoretical and experimental data on the diffusion properties of submicrocrystalline and nanocrystalline materials has been gained in the literature [4][5][6][7][8][9][10][11][12] to date. Specialized phenomenological models of the grain boundary diffusion in these materials have been developed [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Investigations and computer simulations of the intergrain diffusion in submicro-and nanocrystalline metals

et al. 2008

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Investigations of the features of the diffusion along grain boundaries and of the diffusion-controlled processes in submicroscopic and nanocrystalline materials produced by methods of intense plastic deformation are reviewed. To determine the parameters of the diffusion along grain boundaries and triple junctions in metals, which are independent of the results of processing of diffusion experiments based on diffusion models, results of a molecular dynamic investigation of the diffusion in nanocrystalline copper considered as an example are presented. Comparison of the features of grain boundary diffusion in submicroscopic and nanocrystalline materials produced by various methods is performed.

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Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe

Cited by 27 publications

References 20 publications

Anelasticity Study on Motions of Atoms in the Grain Boundary Regions in Nanocrystalline Gold

Anelasticity Study on Motions of Atoms in the Grain Boundary Regions in Nanocrystalline Gold

Microstructural evolution and formation of nanocrystalline intermetallic compound during surface mechanical attrition treatment of cobalt

Investigations and computer simulations of the intergrain diffusion in submicro-and nanocrystalline metals

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