Characterization of a nanocrystalline NiCo electroformed sheet metal

• Published in: Journal of materials science 2021, Vol.56 (2), p.1749-1767
• Main Authors: Kong, Jonathan, Sabatini, Michael, Monaco, Leo, Tam, Jason, McCrea, Jonathan L., Palumbo, Gino, Howe, Jane, Erb, Uwe
• Format: Article
• Language: English
• Subjects: Alloys; Annealing; Anodic polarization; Calorimetry; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Cobalt; Cobalt base alloys; Comparative analysis; Corrosion and anti-corrosives; Crystallography and Scattering Methods; Electroforming; Grain growth; Grain size; Hardness; Intermetallic compounds; Low temperature; Materials Science; Metal sheets; Metals & Corrosion; Nanocrystals; Nickel; Polymer Sciences; Sheet-metal; Solid Mechanics; Thermal stability
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-020-05325-8

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. Graphic abstract