| Summary: | The processing route of Sm<sub>2</sub>Fe<sub>17</sub> carbides is shorter than that of nitrides, which can potentially be used for cost-effective mid-performance magnets’ production. The magnetic properties of Sm<sub>2</sub>Fe<sub>17</sub>C<sub><i>x</i></sub> compounds can be controlled at the annealing step, which allows them to be used for a variety of applications. In this work, X-ray diffraction (XRD) analysis, Mössbauer spectroscopy, scanning and transmission electron microscopy (SEM, TEM) and vibrating sample magnetometry (VSM) were used for characterization of the structure and magnetic properties of Sm<sub>2</sub>Fe<sub>17</sub>C<i><sub>x</sub></i> compounds. The powder samples were prepared by high-energy ball milling of Sm<sub>2</sub>Fe<sub>17</sub> mixtures with carbon nanotubes (CNT) or graphite with subsequent annealing. The formation of Sm<sub>2</sub>Fe<sub>17</sub>C<i><sub>x</sub></i> compounds after annealing was followed by the formation of α-Fe and amorphous Sm<sub>2</sub>O<sub>3</sub>. The hyperfine field values of Fe atoms of all the Sm<sub>2</sub>Fe<sub>17</sub> lattice sites increased by 12% on average after annealing that was caused by carbon diffusion. The coercivity of the samples peaked after annealing at 375 °C. The samples with CNT demonstrated an increase of up to 14% in coercivity and 5% in specific remanence in the range of 250–375 °C annealing temperatures.
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