@conference{
author = "Mitrović, Nebojša and Nedeljković, Borivoje and Obradović, Nina and Orelj, Jelena and Aleksić, Sanja and Pavlović, Vladimir B.",
year = "2024",
abstract = "This study focuses on two ferromagnetic materials as representative of soft (MnZn ferrites) ceramics and semi-hard (FeCo-2wt%V) alloys, both with unique properties in a wide specter of magnetic materials. Recently, a variety of technologies have been examined for MnZn ferrite production: Powder/Ceramic Injection Moulding (PIM/CIM), chemical co-precipitation method, conventional ceramic processing, sol-gel or microemulsion. MnZn ferrites are one of the most common electronic ceramics for application as a material for microwave components (radiofrequency transformers, antennas, transducers, inductors, magnetic fluids, sensors…). They attracted attention due to the wide range of relative magnetic permeability values (from 103 to 104), high electrical resistivity (consequently low magnetic losses) as well as high thermal stability (high saturation magnetic flux density at high temperatures (Bs > 0.4 T @ 100 OC) and a relatively high Curie temperature (about 230 OC). Toroidal samples with dimensions appropriate for applications in microelectronics (inner diameter 3.5 mm, outer diameter 7 mm, height 2 mm) exhibit very stable maximum magnetic permeability in the frequency range from 50 Hz (μr ≈ 480) to 10 kHz (μr ≈ 450) @ 200 A/m. Active power referred to unit mass of about 30 W/kg was recorded at a frequency of 1 kHz (@ 280 mT. Those results were competitive with the catalog data for MnZn components devoted to applications in electronics. Magnetically semi-hard near equiatomic FeCo-2V iron-cobalt based alloy is known for its exceptional combination of high values of saturation magnetic flux density BS and Curie temperature TC (about 950 OC - it is a unique alloy with this property). Binary alloys of Fe − Co systems containing 33-55 wt.% Co are very brittle, but the addition of about 2 wt.% V prevents transformation into an ordered superlattice structure and enables a relatively high value of electrical resistivity (V as alloying element provides very good mechanical and suitable electrical properties compared to other alloying elements, W, Ti, Mo, Mn, Ta, Cu). The XRD patterns of FeCo-2wt%V (FeCoV) alloy produced by Metal Injection Moulding (MIM) technology exhibit the main diffraction peak of the α'-FeCo phase (crystal structure type B2) which increases with an increase in sintering temperature up to 1460 OC. The mechanical hardness does not coincide with the magnetic hardness, i.e. the material with the highest HV10 (value of 348) shows the lowest coercive force HcJ (about 18.4 Oe). Magnetic hardness is associated with the magnetic obstacles that prevent easy movement of magnetic domain walls (“pinning” effect). However, for mechanical hardness, the movement of dislocations, i.e. the prevention of this movement, is crucial (the elements in microstructure are highly efficient in blocking the movement of dislocations, but not that of the Bloch magnetic domain walls). As the hysteresis losses are proportional to the frequency (~ f) and eddy-current losses are proportional to the square of frequency (~ f2) it was performed separation between these two components from total magnetic power (active) losses. Numerical fitting of this functionality on frequency was performed and analyzed, as intermetallic FeCoV components can be used competitively in strategic applications, for example, the aerospace motor rotor.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XII New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 18-20. September 2024",
title = "Magnetically soft and semi-hard materials",
pages = "32-33",
url = "https://hdl.handle.net/21.15107/rcub_dais_16791"
}