Nanocrystalline growth and grain-size effects in Au–Cu electrodeposits

Jankowski, Alan F.; Saw, C. K.; Harper, Jennifer F.; Vallier, Bobby F.; Ferreira, James; Hayes, Jeffrey P.

doi:10.1016/j.tsf.2005.08.149

Cited by 32 publications

(59 citation statements)

References 24 publications

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“…The electrodeposition process to produce free-standing Au-Cu foils with 1-20 wt.% Cu has been described in detail [3]. In brief, a 1.5 liter cyanoalkaline solution is used to electroplate a 10-20 µm thick Au-Cu foil onto a 12 cm 2 substrate of titanium.…”

Section: Experimental and Analysis Methodsmentioning

confidence: 99%

“…the (111), is used to determine Table 1 for each Au-Cu sample set. The nominal composition for each foil is listed as determined [3] to within ±1 wt.% from the energy dispersive x-ray analysis. For all samples, it is seen that the grain size computed using the (111)…”

Section: Nanocrystalline Size and Stabilitymentioning

confidence: 99%

“…To assess stabilization of nanocrystalline Au-Cu through an alloy addition, Sn was added to the standard bath [3] used for Au-Cu electrodeposition. In this case, the 1500 ml solution bath gm NaOH.…”

Section: Nanocrystalline Size and Stabilitymentioning

confidence: 99%

“…The process of pulsed electrodeposition provides a path to control the as-deposited grain size, e.g. of nanocrystalline Au 1-x Cu x alloys [3]. The electrodeposition parameters of cell potential, current density, and pulse duration are modeled [4] to the measurements of the crystallite size within the Au-Cu foil.…”

Section: Introductionmentioning

confidence: 99%

“…A comparison to the assessment of bulk diffusion kinetics in Au-Cu foils at low temperatures is made through the use of concentration waves [10] and the microscopic theory [11] of diffusion. This reference approach provides a low-temperature benchmark for bulk diffusion kinetics [12] normally associated with the hightemperature mobility of the Au 198 tracer isotope in Cu [13] and Au [14]. Also, since grain size coarsening of nanocrystalline Au-Cu foils at low temperature is anticipated, a path to stabilize the nanostructure of the binary Au-Cu alloy is proposed through the addition of a metal with a dissimilar crystallographic structure.…”

Section: Introductionmentioning

confidence: 99%

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The thermal stability of nanocrystalline Au–Cu alloys

2006

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Grain refinement to the nanocrystalline scale is known to enhance physical properties as strength and surface hardness. For the case of Au-Cu alloys, development of the pulsed electroplating has led to the functional control of nanocrystalline grain size in the as-deposited condition. The thermal aging of Au-Cu electrodeposits is now investigated to assess the stability of the nanocrystalline grain structure and the difference between two diffusion mechanisms. The mobility of grain boundaries, dominant at low temperatures, leads to coarsening of grain size whereas at high temperature the process of bulk diffusion dominates. Although the kinetics of bulk diffusion are slow below 500 K at 10 -20 cm 2 ·sec, the kinetics of grain boundary diffusion are faster at 10 -16 cm 2 ·sec. The diffusivity values indicate that the grain boundaries of the asdeposited nanocrystalline Au-Cu are mobile and sensitive to low-temperature anneal treatments affecting the grain size, hence the strength of the material.

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Section: Experimental and Analysis Methodsmentioning

confidence: 99%

Section: Nanocrystalline Size and Stabilitymentioning

confidence: 99%

Section: Nanocrystalline Size and Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The thermal stability of nanocrystalline Au–Cu alloys

2006

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A Review of Fatigue Behavior in Nanocrystalline Metals

2009

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Nanocrystalline metals have been shown to exhibit unique mechanical behavior, including break-down in Hall-Petch behavior, suppression of dislocation-mediated plasticity, induction of grain boundary sliding, and induction of mechanical grain coarsening. Early research on the fatigue behavior of nanocrystalline metals shows evidence of improved fatigue resistance compared to traditional microcrystalline metals. In this review, experimental and modeling observations are used to evaluate aspects of cyclic plasticity, microstructural stability, crack initiation processes, and crack propagation processes. In cyclic plasticity studies to date, nanocrystalline metals have exhibited strongly rate-dependent cyclic hardening, suggesting the importance of diffusive deformation mechanisms such as grain-boundary sliding. The cyclic deformation processes have also been shown to cause substantial mechanicallyinduced grain coarsening reminiscent of coarsening observed during large-strain monotonic deformation of nanocrystalline metals. The crack-initiation process in nanocrystalline metals has been associated with both subsurface internal defects and surface extrusions, although it is unclear how these extrusions form when the grain size is below the scale necessary for persistent slip band formation. Finally, as expected, nanocrystalline metals have very little resistance to crack propagation due to limited plasticity and the lack of crack path tortuosity among other factors. Nevertheless, like bulk metallic glasses, nanocrystalline metals exhibit both ductile fatigue striations and metal-like Paris-law behavior. The review provides both a comprehensive critical survey of existing literature and a summary of key areas for further investigation.

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Characterization of Strain-Rate Sensitivity and Grain Boundary Structure in Nanocrystalline Gold-Copper Alloys

Nyakiti

Jankowski

2009

Metall Mater Trans A

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The power-law dependence of strength on strain rate provides a measure of the strain-rate sensitivity. In general, strength increases as grain size decreases from the microscale into the nanoscale regime for many cubic metals. The method of microscratch testing is used to measure microhardness in order to evaluate material strength. The strain-rate dependence of hardness is measured by varying the microscratch velocity. New results for nanocrystalline gold alloys show that the exponent (m) of the power-law dependence of stress on strain rate increases to 0.20 as grain size decreases to values less than 10 nm. A high-resolution electron microscopy examination of grain boundary structure reveals that an increase in the strain-rate sensitivity exponent (m) is found with an increase in the grain boundary misorientation.

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Nanocrystalline growth and grain-size effects in Au–Cu electrodeposits

Cited by 32 publications

References 24 publications

The thermal stability of nanocrystalline Au–Cu alloys

The thermal stability of nanocrystalline Au–Cu alloys

A Review of Fatigue Behavior in Nanocrystalline Metals

Characterization of Strain-Rate Sensitivity and Grain Boundary Structure in Nanocrystalline Gold-Copper Alloys

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