Microstructure and Properties of Electrodeposited Nanocrystalline Ni-Co-Fe Coatings

• Published in: Materials Vol. 14; no. 14; p. 3886
• Main Authors: Ledwig, Piotr, Kac, Malgorzata, Kopia, Agnieszka, Falkus, Jan, Dubiel, Beata
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 12.07.2021; MDPI
• Subjects: Alloys; Chemical composition; Chemical elements; Coated electrodes; Coatings; Cobalt base alloys; Coercivity; Composition effects; Corrosion potential; corrosion properties; Corrosion resistance; Diameters; electrodeposition; Electrodes; Hysteresis loops; Investigations; Ion concentration; Iron; Magnetic properties; Magnetic recording; Magnetic storage; Magnetometers; Mechanical properties; Microhardness; Microstructure; microstructure characterization; Molecular beam epitaxy; Morphology; nanocrystalline alloys; Nanocrystals; Nanostructured materials; Nanotechnology; Ni-Co-Fe coatings; Nickel; Phase composition; Recording instruments; Software; Solid solutions; Superconducting quantum interference devices; United States > US; Switzerland
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14143886

Materials based on Ni-Co-Fe alloys, due to their excellent magnetic properties, attract great attention in nanotechnology, especially as candidates for high-density magnetic recording media and other applications from spintronic to consumer electronics. In this study, Ni-Co-Fe nanocrystalline coatings were electrodeposited from citrate-sulfate baths with the Ni2+:Co2+:Fe2+ ion concentration ratios equal to 15:1:1, 15:2:1, and 15:4:1. The effect of the composition of the bath on the morphology, microstructure, chemical composition, microhardness, and magnetic properties of the coatings was examined. Scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffractometry (XRD), and energy dispersive X-ray spectroscopy (EDS) were used to study surface morphology, microstructure, chemical, and phase composition. Isothermal cross-sections of the Ni-Co-Fe ternary equilibrium system for the temperature of 50 °C and 600 °C were generated using the FactSage package. Magnetic properties were analyzed by a superconducting quantum interference device magnetometer (SQUID). All the coatings were composed of a single phase being face-centered cubic (fcc) solid solution. They were characterized by a smooth surface with globular morphology and a nanocrystalline structure of grain diameter below 30 nm. It was determined that Ni-Co-Fe coatings exhibit high hardness above 4.2 GPa. The measurements of hysteresis loops showed a significant value of magnetization saturation and small coercivity. The microstructure and properties of the obtained nanocrystalline coatings are interesting in terms of their future use in micromechanical devices (MEMS).