Room temperature creep behavior of nanocrystalline nickel produced by an electrodeposition technique

Wang, Ning; Wang, Zhirui; Aust, K.T.; Erb, U.

doi:10.1016/s0921-5093(97)00124-x

Cited by 260 publications

(147 citation statements)

References 24 publications

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“…60͒ and in electroplated Ni ͑claimed to be porosity free͒. 70,71 There are theoretical arguments for expecting that the Hall-Petch relation ceases to be valid for grain sizes below ϳ20 nm: as the grain size becomes too small, dislocation pileups are no longer possible, and the usual explanation for Hall-Petch behavior does not apply. 59,72,73 Many models have been proposed to explain why a reverse Hall-Petch effect is sometimes seen.…”

Section: B Reverse Hall-petch Effectmentioning

confidence: 99%

Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

et al. 1999

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Nanocrystalline metals, i.e., metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength. We present atomic-scale simulations of the plastic behavior of nanocrystalline copper. The simulations show that the main deformation mode is sliding in the grain boundaries through a large number of uncorrelated events, where a few atoms ͑or a few tens of atoms͒ slide with respect to each other. Little dislocation activity is seen in the grain interiors. The localization of the deformation to the grain boundaries leads to a hardening as the grain size is increased ͑reverse Hall-Petch effect͒, implying a maximum in hardness for a grain size above the ones studied here. We investigate the effects of varying temperature, strain rate, and porosity, and discuss the relation to recent experiments. At increasing temperatures the material becomes softer in both the plastic and elastic regime. Porosity in the samples result in a softening of the material; this may be a significant effect in many experiments. ͓S0163-1829͑99͒05941-X͔

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Section: B Reverse Hall-petch Effectmentioning

confidence: 99%

Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

et al. 1999

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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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“…Meanwhile, other authors have reported that GBS can occur at room temperature in nanocrystalline Mg, 11) as well as in other nanocrystalline metals such as Ni 12) and Au.…”

Section: Introductionmentioning

confidence: 99%

Grain-Boundary Sliding in AZ31 Magnesium Alloys at Room Temperature to 523 K

et al. 2003

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Rolled sheets of AZ31 Mg alloys were subjected to tensile testing at temperatures ranging from room temperature to 523 K. The occurrence of grain-boundary sliding (GBS) at room temperature was demonstrated by the displacement of scribed lines across grain boundaries of deformed samples. Surface relief of deformed samples was measured by use of a scanning laser microscope. GBS strain was calculated from the measured surface step height, and its temperature dependence was analyzed by a Dorn-type constitutive equation. GBS above 423 K was found to be pure GBS that was activated by resolved applied shear stress acting on grain boundaries. The activation energy for GBS was found to be 80 kJ/mol, which is in agreement with the activation energy for grain boundary diffusion. Meanwhile, GBS below 373 K was found to be slipinduced GBS, and its extent was found to be significantly greater than that expected from extrapolation of high-temperature values. The slipinduced GBS is considered to occur by plastic compatibility conditions in the presence of plastic strain anisotropy and by absorption and dissociation of lattice dislocations at grain boundaries.

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Room temperature creep behavior of nanocrystalline nickel produced by an electrodeposition technique

Cited by 260 publications

References 24 publications

Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

Strain rate sensitivity of nanocrystalline Au films at room temperature

Grain-Boundary Sliding in AZ31 Magnesium Alloys at Room Temperature to 523 K

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