## 2 Materials and Methods  
Fe ingots of about 20-25 g were prepared via the arc melting technique from commercial iron lumps (Alfa Aesar) with a purity higher than 99.99%. The resulting Fe ingots were transformed into powders via the gas atomization method using a homemade atomization plant. The schematic structure of the gas atomization plant is shown in Figure 1.  
The Fe ingot to be melted was placed in a quartz crucible provided in the lower part with a circular ejection nozzle and heated via induction to temperatures up to 50 \({}^{\circ}\)C above the liquidus temperature of Fe (1538 \({}^{\circ}\)C) in order to obtain appropriate viscosity and surface tension values that allowed for the steady flow of the liquid jet. A photocell located at the top of the quartz crucible was used to measure the surface temperature of the melted iron after it had been previously calibrated with a high-precision pyrometer. Both the atomizing chamber and the melting chamber were previously vacuumed to a pressure of 10\({}^{-3}\) mbar and flushed 4 times with nitrogen gas and refilled with nitrogen to reduce the oxygen content. Before being ejected, the melt was maintained for five minutes under a nitrogen pressure between 1 and 3 bar. Induction melting creates currents of liquid that facilitate the continuous movement of the material, resulting in the exposure of the liquid iron to the nitrogen gas that fills the melting chamber. The flow of the liquid metal is initiated by the sudden decrease in pressure in the atomizing chamber to 0.2 bar. At the same time, the atomization gas, the pressure of which varied between 10 and 20 bars, hit the molten iron jet, resulting in the disintegration of the melt into droplets. The atomizing gas exit nozzle was in the form of a continuous annular slot with a width of 300 \(\upmu\)m and concentric with the melt ejection nozzle (right Figure 1). The diameter of the ejection nozzle varied between 100 and 300 \(\upmu\)m. The angle between the direction of the liquid jet and that of the gas jet was kept constant at 45\({}^{\circ}\) in all experiments. The distance between the ejection nozzle and the particle collector was tested and established as the optimal value of 120 cm. After atomization, the collected powders were immediately transferred to a nitrogen-filled glovebox without exposure to air to prepare the samples for structural, morphological, and magnetic measurements. The structural analysis was carried out via X-ray diffraction (XRD) in a Bruker AXS D8--Advance diffractometer over an angular range 20-90\({}^{\circ}\) with a step of 0.02\({}^{\circ}\) and a counting time of 2 s per step using conventional Cu-K\(\alpha\) incident radiation. The Rietveld refinements of the XRD patterns were performed using MAUD software [38]. The microstructure and morphology of the sample was investigated using a scanning electron microscope, FIB/FE--SEM Cross--Beam Carl Zeiss NEON 40 EsB (Oberkochen, Germany), equipped with an energy dispersive X-ray spectroscopy (EDS) module. The free software Image J ([[https://imagej.net/ij/](https://imagej.net/ij/)]([https://imagej.net/ij/](https://imagej.net/ij/)), accessed on 24 September 2023) was used to characterize the size distribution of the particles [39]. Magnetic measurements were performed using a Vibrating Sample Magnetometer (VSM) (Lake Shore VSM 7410, Westerville, OH, USA) in a maximum applied field of 20 kOe at room temperature.