Characterization of a nanocrystalline NiCo electroformed sheet metal
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Characterization of a nanocrystalline NiCo electroformed sheet metal Jonathan Kong1, Michael Sabatini1, Leo Monaco1, Jason Tam1, Jonathan L. McCrea2, Gino Palumbo2, Jane Howe1,3, and Uwe Erb1,* 1
Department of Materials Science and Engineering, University of Toronto, 184 College Street, Suite 140, Toronto, ON M5S 3E4, Canada 2 Integran Technologies, Inc, 6300 Northam Drive, Mississauga, ON L4V 1H7, Canada 3 Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E4, Canada
Received: 18 May 2020
ABSTRACT
Accepted: 3 September 2020
A novel electroformed nanocrystalline nickel cobalt alloy (n-NiCo) developed for sheet metal applications was investigated in terms of microstructure, as well as mechanical, thermal stability, and corrosion properties. The as-received material with a grain size of 18 ± 5 nm exhibited enhanced hardness compared with conventional polycrystalline NiCo mainly due to the Hall–Petch strengthening effect. Differential scanning calorimetry and annealing treatment results revealed that the n-NiCo was stable up to 200 °C for at least 1 h, and the onset of abnormal grain growth was observed when the material was annealed to 250 °C. While low-temperature annealing treatment was shown to increase the hardness of the material slightly, annealing at temperatures of 300 °C and above resulted in a reduction in hardness due to rapid normal grain growth. The n-NiCo sheet exhibited mixed Ni/Co anodic polarization behavior in environments of varying pH.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Nathan Mara.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05325-8
J Mater Sci
GRAPHIC ABSTRACT
Introduction Nanostructured metals have been studied intensively over the past few decades due to their outstanding mechanical, physical and chemical properties (e.g., [1–3]). These enhanced properties make them excellent materials for high value-added applications in electronics, magnetic storage and surface coatings in the aerospace, automotive and other industries. However, many production methods for nanomaterials are limited by low production rates, difficult scalability and high production costs. One common process that mitigates these drawbacks is electrodeposition/electroforming which was first developed in the late 19800 s to early 1990s [4–7]. This approach can produce a wide range of metals, alloys, and composites with grain size of less than 100 nm (e.g., [8–18]). It is an economical process with high production rates and the deposits have minimal size and shape limitations [19–22]. For example, the materials can be applied as thin or thick coatings on various substrates or electroformed as free-standing bulk materials.
Nickel is often used in applications where high strength, corrosion, and wear resistance are important. The electrodeposition/electroforming of nanocrystalline Ni is fairly well understood and currently used in numerous industrial appli
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