## 1 Introduction  
NdFeB permanent magnets have been investigated since 1983 [1; 2; 3] and continue to be investigated [4; 5] due to their high energy density (-450 kJm\({}^{-3}\)) [6], which makes them useful for a number of different applications including acoustic transducers, air conditioning, electric bikes, wind turbines, hybrid and electric cars and hard disk drives, among others [7]. For these reasons, efforts are being devoted to obtaining an improvement in their magnetic and physical properties. Nanocomposite permanent magnets are composed of soft (x-Fe or Fe\({}_{3}\)B) and hard (Nd\({}_{2}\)Fe\({}_{14}\)B) nanocrystalline magnetic phases and attract a great deal of interest because they exhibit unusual properties, such as a remanence relation (Mr/Ms) larger than 0.5 (the Stoner-Wohlfarth limitation) due to the exchange coupling between these two phases [8]. Among earlier works into nanocomposite magnet, a study was carried out by [PERSON], [PERSON] et al. [9] that investigated Fe\({}_{3}\)B/Nd\({}_{2}\)Fe\({}_{14}\)B with magnetic properties of 0.3 T and 93 kJm\({}^{-3}\) for coercive and magnetic energy, respectively. After these works, different theoretical models [10; 11; 12] were proposed in order to improve the general understanding of exchange-coupled nanocomposite magnets. A number of studies were reported for thin films; for example, [PERSON], [PERSON] et al. [13] investigated Nd\({}_{2}\)Fe\({}_{14}\)B/FeCo anisotropic nanocomposite films and obtained values of the maximum energy product between 400 and 500 kJm\({}^{-3}\) through an exchange-coupling mechanism. On the other hand, [PERSON] et al. [4] recently investigated bonded magnets of NdFeB with SrFe\({}_{12}\)O\({}_{19}\) ferrite by additive manufacturing (3D printing); for a sample with 20 wt% of ferrite, they obtained a relatively low surface roughness of \(\sim\)6 \(\upmu\)m and a tensile strength of 12 MPa. However, they obtained a decrease in the magnetic properties of saturation magnetization (M\({}_{\mathrm{s}}\)), remanent magnetization (M\({}_{\mathrm{r}}\)), coercive field (H\({}_{\mathrm{c}}\)) and maximum energy product (BH)\({}_{\mathrm{max}}\) upon increasing the content wt% of ferrite. Other recent work on the NdFeB system using the same principle was reported in [5], where the phase and hyperfine structure of melt-spun nanocrystalline (Ce\({}_{1-\mathrm{x}}\)Nd\({}_{\mathrm{x}}\))\({}_{16}\)Fe\({}_{78}\)B\({}_{6}\) alloys were studied. These results suggest that alloys are composed specifically of the (NdCe)\({}_{2}\)Fe\({}_{14}\)B phase; however, phases such as (CeNd)Fe\({}_{2}\) and (CeNd)Fe\({}_{4}\)B\({}_{4}\) have also been identified. The Mossbauer fit was carried out using six sextets and two doublet components; the average magnetic hyperfine field using Mossbauer and the magnetic properties M\({}_{\mathrm{s}}\), H\({}_{\mathrm{c}}\) and (BH)\({}_{\mathrm{max}}\) increased for compositions from x = 0 to x = 0,7.These properties are sensible to the type of elements of the hard [14; 15; 16; 17; 18; 19] and soft phases [14; 20], to the grain size of the hard phase [15; 16; 21; 22; 23; 24] and to the different techniques used to prepare them [25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36]. In addition to studies of magnetic properties, it is also important to consider the mechanical properties of permanent magnets. Many efforts have been made to find ways to improve these mechanical properties [2; 37]; previous efforts have mainly focused on modifying the compositions by the addition of doping elements such as Al, Ti, Nb, Ga, Cu, Cr, Zr, etc. [38; 39].