Evolution of the magnetic properties of melt-spun NdFeB alloys with the addition of waste NdFeB magnet

The importance of NdFeB magnets is increasing rapidly with the development of electronic technologies. Accordingly, the reserves of rare earth elements are decreasing day by day, and their costs are increasing. Therefore, effective recovery of waste magnets is critical. Within the scope of this study, NdFeB alloys (30 wt% Nd, 69 wt% Fe, and 1 wt% B) without waste magnet and containing 15 wt% and 30 wt% waste magnet were produced by the melt-spinning method. According to the X-ray diffraction results, a semi-crystalline structure was obtained in all of the samples. With an increase in the use of waste magnets in NdFeB alloy, the (Nd, Dy, and Pr)(2)Fe14B hard-magnetic phase has formed instead of the Nd2Fe14B hard-magnetic phase because Dy and Pr exist in the waste magnets. In addition, there was a decrease in the crystal sizes of alpha-Fe soft magnetic and hard-magnetic phases. The Curie temperatures of the samples varied between 290 and 310 degrees C, and crystallization temperatures varied between 350 and 380 degrees C. The Curie and crystallization temperatures were obtained as 308.17 and 377.67 degrees C, respectively, in the sample using 30 wt% waste magnets from differential scanning calorimetry analysis. The highest coercivity, maximum energy product, remanence, and lowest saturation magnetization were obtained as 732.95 kA/m, 102.14 J/m(3), 57.94 emu/g, and 90.86 emu/g, respectively, in the sample using 30 wt% waste magnets.