Creep of nanocrystalline Cu, Pd, and Al-Zr

Sanders, Paul G.; Rittner, M.; Kiedaisch, E.; Weertman, J.; Kung, H.; Lu, Yeqing

doi:10.1016/s0965-9773(97)00096-2

Cited by 106 publications

(23 citation statements)

References 10 publications

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“…Steadystate creep rates for nanocrystalline face-centered cubic (fcc) metals at room temperature have been reported to be of the order of 10 À10 -10 À7 s À1 [17,18]. However, these rates are quite lower than the primary creep rate which is 1359-6454/$36.00 Ó 2010 Acta Materialia Inc.…”

Section: Introductionmentioning

confidence: 99%

Strain rate sensitivity of nanocrystalline Au films at room temperature

et al. 2010

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Dimitrios, "Strain rate sensitivity of nanocrystalline Au films at room temperature" (2010) AbstractThe effect of strain rate on the inelastic properties of nanocrystalline Au films was quantified with 0.85 and 1.76 lm free-standing microscale tension specimens tested over eight decades of strain rate, between 6 Â 10 À6 and 20 s À1 . The elastic modulus was independent of the strain rate, 66 ± 4.5 GPa, but the inelastic mechanical response was clearly rate sensitive. The yield strength and the ultimate tensile strength increased with the strain rate in the ranges 575-895 MPa and 675-940 MPa, respectively, with the yield strength reaching the tensile strength at strain rates faster than 10 À1 s À1 . The activation volumes for the two film thicknesses were 4.5 and 8.1 b 3 , at strain rates smaller than 10 À4 s À1 and 12.5 and 14.6 b 3 at strain rates higher than 10 À4 s À1 , while the strain rate sensitivity factor and the ultimate tensile strain increased below 10 À4 s À1 . The latter trends indicated that the strain rate regime 10 À5 -10 À4 s À1 is pivotal in the mechanical response of the particular nanocrystalline Au films. The increased rate sensitivity and the reduced activation volume at slow strain rates were attributed to grain boundary processes that also led to prolonged (5-6 h) and significant primary creep with initial strain rate of the order of 10 À7 s À1 .

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Section: Introductionmentioning

confidence: 99%

Strain rate sensitivity of nanocrystalline Au films at room temperature

et al. 2010

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“…[2] Recent investigations of ultrafinegrained (UFG) materials have concentrated mainly on structural characterization, [3][4][5] microhardness variation, [6,7] mechanical properties, [8,9] elastic and damping properties, [10] fatigue, [11] and creep. [12] Several models have been also developed to relate the mechanical properties of the UFG metals to the evolution of the microstructure and texture. [13][14][15] Equal-channel angular pressing (ECAP) has been identified as an efficient method for obtaining submicrocrystalline (grain size d < 1 lm) or nanocrystalline (d < 100 nm) grain sizes in bulk metallic materials.…”

Section: Introductionmentioning

confidence: 99%

Microstructure of Equal-Channel Angular Pressed Cu and Cu-Zr Samples Studied by Different Methods

Kužel

Janeček

Matěj

et al. 2009

Metall Mater Trans A

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Polycrystalline samples of technical-purity Cu (99.95 wt pct) and Cu with 0.18 wt pct Zr have been processed at room temperature by equal-channel angular pressing (ECAP). The microstructure evolution and its fragmentation after ECAP were investigated by transmission electron microscopy (TEM), electron backscattered diffraction (EBSD), positron annihilation spectroscopy (PAS), and by X-ray diffraction (XRD) line-profile analysis. The first two techniques revealed an increase in the fraction of high-angle grain boundaries (HAGBs), with increasing strain reaching the value of 90 pct after eight ECAP passes. The increase was more pronounced for pure Cu samples. The following two kinds of defects were identified in ECAP specimens by PAS: (1) dislocations that represent the dominant kind of defects and (2) small vacancy clusters (so-called microvoids). A detailed XRD line-profile analysis was performed by the analysis of individual peaks and by total profile fitting. A slight increase in the dislocation density with the number of ECAP passes agreed with the PAS results. Variations in microstructural features obtained by TEM and EBSD can be related to the changes in the XRD line-broadening anisotropy and dislocation-correlation parameter.

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“…In addition to grain boundary sliding, diffusion along grain boundaries [333][334][335] and along triple junctions [336][337][338][339][340] has been proposed to account for the plastic deformation without dislocation motion below the critical grain size. Diffusion is particularly relavant to the deformation of nanocrystalline metals because typical dislocation mechanisms are suppressed and grain-boundary-controlled deformation processes become dominant [308].…”

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confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

833

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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Creep of nanocrystalline Cu, Pd, and Al-Zr

Cited by 106 publications

References 10 publications

Strain rate sensitivity of nanocrystalline Au films at room temperature

Strain rate sensitivity of nanocrystalline Au films at room temperature

Microstructure of Equal-Channel Angular Pressed Cu and Cu-Zr Samples Studied by Different Methods

Nanocrystalline materials and coatings

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