Thermal stability of nanocrystalline gold and copper prepared by gas deposition method

Okuda, S.; Kobiyama, Mamoru; Inami, Takashi; Takamura, S.

doi:10.1016/s1359-6462(01)00825-9

Cited by 33 publications

(12 citation statements)

References 14 publications

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“…Inert gas condensation combined with thermal evaporation is commonly used to fabricate metallic and metal-oxide powders with a well defined and narrow size distribution [9,17,30,[68][69][70][71][72][73][74]. This technique was originally introduced by Ganqvist and Buhrman [75] in 1976 and developed by Gleiter in 1981 [76].…”

Section: Physical Vapor Depositionmentioning

confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

837

345

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In recent years, near-nano (submicron) and nanostructured materials have attracted increasingly more attention from the materials community. Nanocrystalline materials are characterized by a microstructural length or grain size of up to about 100 nm. Materials having grain size of $0.1 to 0.3 mm are classified as submicron materials. Nanocrystalline materials exhibit various shapes or forms, and possess unique chemical, physical or mechanical properties. When the grain size is below a critical value ($10-20 nm), more than 50 vol.% of atoms is associated with grain boundaries or interfacial boundaries. In this respect, dislocation pile-ups cannot form, and the Hall-Petch relationship for conventional coarse-grained materials is no longer valid. Therefore, grain boundaries play a major role in the deformation of nanocrystalline materials. Nanocrystalline materials exhibit creep and super plasticity at lower temperatures than conventional micro-grained counterparts. Similarly, plastic deformation of nanocrystalline coatings is considered to be associated with grain boundary sliding assisted by grain boundary diffusion or rotation. In this review paper, current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings will be addressed. Particular attention is paid to the properties of transition metal nitride nanocrystalline films formed by ion beam assisted deposition process. #

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Section: Physical Vapor Depositionmentioning

confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

837

345

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“…Most reported studies of the sintering of nanosized metallic or ceramic powders [1][2][3][4][5][6][7][8][9][10] found that grain growth is so rapid and so significant that the nanosized powders would grow to greater than one or several hundred nanometers as soon as a powder compact is heated, losing nanocrystalline features. Controlling and minimizing grain growth is indeed one of the most important challenges for manufacturing bulk nanocrystalline materials by the route of sintering of nanosized powders.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Initial Coarsening During Sintering of Nanosized Powders

Wang

Fang

Hwang

2011

Metall Mater Trans A

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Grain growth during sintering is a critical issue for the manufacture of nanocrystalline bulk materials from nanosized powders. The grain growth process during sintering can be viewed as consisting of two parts: initial coarsening during early and intermediate stages of sintering and latter stage grain growth during the final stage of sintering. The latter stage grain growth is the normal grain growth that has been well studied and reported in the literature. The initial coarsening, which often inevitably causes a material to lose nanoscaled grain size characteristics, however, is not well studied at all. In this investigation, the initial coarsening during sintering of nanosized powders was studied by both nonisothermal and isothermal experimental techniques using tungsten as an example material. The results show that the initial coarsening during the heat-up process of a sintering cycle is sufficient to increase the grain size beyond the nanoscale. The kinetics of initial coarsening is found to be linear rather than polynomial, as predicted by the conventional power law of grain growth. The analysis of activation energies showed that surface diffusion is the primary mechanism for interparticle mass transport during the initial coarsening. The linear kinetic behavior could be attributed to the pinning of grain boundaries by surface grooves and high concentration of defects as the result of the synthesis of nanosized powders.

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“…Using these values, together with the H 0 and k y values (1.01 GPa and 0.11 MPa m À1/2 , respectively) determined above, the hardness due to GB and TB strengthening can be calculated by Eq. (8). The calculated values are 2.3 and 2.16 GPa for the 1.0 keV IBAD-Cu film before and after annealing, respectively.…”

Section: Hardening Due To Twin Boundariesmentioning

confidence: 86%

“…(7) and (8) [17,19]. An effective domain size (d eff ) has been suggested, with which the Hall-Petch relation for the conventional metals can be extended to nt-metals [19], as:…”

Section: Hardening Due To Twin Boundariesmentioning

confidence: 99%

“…This relation is valid even down to nanometer regime and the nanocrystalline (nc) metals have been found to exhibit significantly higher mechanical strength than that of their coarse-grained counterparts [2][3][4][5]. However, a main drawback for nc metals is their microstructural susceptibility: rapid grain coarsening and, consequently, a strength reduction are commonly observed in nc metals due to the high volume fraction of GBs [6][7][8]. This microstructural instability is a challenge for high temperature applications of nc metals.…”

Section: Introductionmentioning

confidence: 99%

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