Characterization of a nanocrystalline NiCo electroformed sheet metal

Kong, Jonathan; Sabatini, Michael; Monaco, L. Lo; Tam, Jason; McCrea, J.L.; Palumbo, G.; Erb, U.

doi:10.1007/s10853-020-05325-8

Cited by 10 publications

(1 citation statement)

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“…The majority of research groups have attributed the excellent micromechanical properties of eNiCo alloys, additionally to their alloy composition, i.e., the solid solution strengthening effect, to their nanocrystalline (nC) microstructure, wherein the materials with grain size < 100 nm are categorized as nC-materials [ 18 , 19 , 20 ]. For, e.g., comparing two eNiCo alloys with similar alloy composition, the alloy with finer grain size possesses higher microhardness values [ 14 ]; i.e., complying with the Hall–Petch relation [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Bath Hydrodynamics on the Micromechanical Properties of Electrodeposited Nickel-Cobalt Alloys

2021

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The influence of bath hydrodynamics on the resultant micromechanical properties of electrodeposited nickel-cobalt alloy system is investigated. The bath hydrodynamics realized by magnetic stirring is simulated using COMSOL Multiphysics and a region of minimum variation in velocity within the electrolytic cell is determined and validated experimentally. Nickel-cobalt alloy and nickel coating samples are deposited galvanostatically (50 mA/cm2) with varying bath velocity (0 to 42 cm/s). The surface morphology of samples gradually changed from granular (fractal dimension 2.97) to more planar (fractal dimension 2.15) growth type, and the according average roughness decreased from 207.5 nm to 11 nm on increasing the electrolyte velocity from 0 to 42 cm/s for nickel-cobalt alloys; a similar trend was also found in the case of nickel coatings. The calculated grain size from the X-ray diffractograms decreased from 31 nm to 12 nm and from 69 nm to 26 nm as function of increasing velocity (up to 42 cm/s) for nickel-cobalt and nickel coatings, respectively. Consecutively, the measured Vickers microhardness values increased by 43% (i.e., from 393 HV0.01 to 692 HV0.01) and by 33% (i.e., from 255 HV0.01 to 381 HV0.01) for nickel-cobalt and nickel coatings, respectively, which fits well with the Hall–Petch relation.

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