20.500.12556/RUL-133245 Spark plasma sintering as an effective texturing tool for reprocessing recycled HDDR Nd-Fe-B magnets with lossless coercivity The low-pressure hot-deformation methodology was applied to reprocess the nanocrystalline hydrogenation–disproportionation–desorption–recombination (HDDR) Nd-Fe-B powders from end-of-life (EOL) permanent magnets’ waste to determine the mechanism of texture development and the resultant improvement in remanence (and BH$_{max}$) in the recycled material. Both the hot-pressed and hot-deformed magnets produced via spark plasma sintering (SPS) were compared in terms of their magnetic properties with respect to forging pressures. Also, a comparison was established with the microstructure to cite the effectiveness of texture development at low deformation rates and pressures which is pivotal for retaining high coercivity. The hot-pressed magnets maintain the high coercivity (better than 100%) of the original recycled powder due to the control of SPS conditions. The hot deformation pressure was varied from 100–150 MPa at 750 °C processing temperature to identify the optimal texture development in the sintered HDDR Nd-Fe-B magnets. The effect of post-hot-deformation thermal treatment was also investigated, which helped in boosting the overall magnetic properties and better than the recycled feedstock. This low-pressure hot deformation process improved the remanence of the hot-pressed magnet by 11% over the starting recycled powder. The M$_r$/M$_S$ ratio which was 0.5 for the hot-pressed magnets increased to 0.64 for the magnets hot-deformed at 150 MPa. Also, a 55% reduction in height of the sample was achieved with the c-axis texture, indicating approximately 23% higher remanence over the isotropic hot-pressed magnets. After hot deformation, the intrinsic coercivity (H$_{Ci}$) of 960 kA/m and the remanence (B$_r$) value of 1.01 T at 150 MPa is indicative that the controlled SPS reprocessing technique can prevent microstructure related losses in the magnetic properties of the recycled materials. This route also suggests that the scrap Nd-Fe-B magnets can be treated with recoverable magnetic properties subsequently via HDDR technique and controlled hot deformation with a follow-up annealing. rare earth permanent magnets anisotropic HDDR Nd$_2$Fe$_{14}$B recycling spark plasma sintering texture development hot deformation true false true Angleški jezik Ni določen Članek v reviji 2021-11-18 09:21:16 2021-11-18 09:21:17 2022-09-12 04:15:28 0000-00-00 00:00:00 2020 0 0 17 str. iss. 3, art. 418 Vol. 10 2020 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 620.1/.2 2075-4701 10.3390/met10030418 33278247 RAZ_Ikram_Awais_2020.pdf RAZ_Ikram_Awais_2020.pdf 1 8140DE3EA9D2C93ED2F96E47FB7E3A77 493cb60f61d09ca245f442c307ff8fc9fdc997b5b1c549370b3c80e905d675cf 9f2188a2-4848-11ec-abdb-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=151142 https://www.mdpi.com/2075-4701/10/3/418 0 947d9a4e-4848-11ec-abdb-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=151141 Fakulteta za strojništvo 0 0 0