## 1 Introduction  
Permanent magnets play a crucial role in various aspects of modern life for applications in \"green energy\" (wind turbines, electric-hybrid cars), automation (and robotics), information technology, magnetic sensors, and magnetic microdevices, and their influence is constantly growing [1; 2; 3; 4; 5]. At the moment, rare earth-based magnets dominate the global magnet market due to their outstanding magnetic performance. However, some of these rare earths, such as neodymium (Nd), praseodymium (Pr), dysprosium (Dy), and terbium (Tb), are listed as critical materials by the US Department of Energy, the International Renewable Energy Agency, and other international institutions [6; 7; 8; 9], and their future use for permanent magnets production is uncertain. Also, the rare earth extraction and separation process is very pollutive, although new separation and extraction methods are constantly being proposed [10; 11; 12; 13; 14]. According to the Motion Control & Motor Association (MCMA), the world's population is expected to reach 9 billion by 2050, and by this time, every human on Earth will be served by three service robots. Furthermore, each robot is expected to contain more than 100 motors. As a result, the demand for permanent magnets is expected to increase significantly in the coming years. This, coupled with increasing concerns about environmental degradation due to the exploitation of rare earths, increasing costs, and availability problems of rare earths, has led to worldwide efforts to search for rare earth free magnetic materials that can be used for the preparation of a new generation of permanent magnets. The ideal permanent magnet should have the following characteristics: an abundant and environmentally friendly element composition, a high saturation magnetization, a high energy product, fairly high coercivity, and a high Curie temperature. The compound \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) fulfills almost all of these requirements, as its constituent materials Fe and N are abundant and environmentally friendly, it possesses a giant saturation magnetization of \(\sim\)2.9 T (\(\sim\)305 emu/g) [15,16], its theoretical energy product is estimated to be two times higher than that of the strongest rare earth magnet [17], it has a Curie temperature of about 540 \({}^{\circ}\)C [18], and the reported coercivity of the \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) compound is about 2 kOe [19]. After the first report by [PERSON] and [PERSON] on the giant saturation magnetization of about 290 emu/g of the \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) phase in the evaporated Fe-N thin film, many researchers have made efforts to reproduce these results. However, it was not until nearly 20 years later that researchers from Hitachi in Japan reported a close value for the saturation magnetization obtained using single-crystal \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) films grown via molecular beam epitaxy [18,20]. Encouraged by the promising magnetic properties demonstrated by thin films, researchers are interested in preparing bulk samples with the same promising magnetic properties as potential precursors for permanent magnets. Thus, magnetic materials containing the \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) phase have been prepared in the form of thin films, foils, rods, ribbons, nanocones, nanopowders, and powders [21, 22, 23, 24, 25, 26, 27, 28, 29, 30]. However, the most suitable precursors for the preparation of permanent magnets are materials in the form of powders or even nanopowders. In the case of the \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) compound, compaction is also a challenge due to the fact that the \(\alpha^{\prime\prime}\)-Fe\({}_{16}\)N\({}_{2}\) compound decomposes at temperatures over 200 \({}^{\circ}\)C [31]. Therefore, high-temperature sintering or spark plasma sintering, the usual methods for compacting Nd-Fe-B permanent magnets, are not feasible methods for preparing these types of permanent magnets.