20.500.12556/RUL-134379 Limitations in the grain boundary processing of the recycled HDDR Nd-Fe-B system Fully dense spark plasma sintered recycled and fresh HDDR Nd-Fe-B nanocrystalline bulk magnets were processed by surface grain boundary diffusion (GBD) treatment to further augment the coercivity and investigate the underlying diffusion mechanism. The fully dense SPS processed HDDR based magnets were placed in a crucible with varying the eutectic alloys Pr$_{68}$Cu$_{32}$ and Dy$_{70}$Cu$_{30}$ at 2–20 wt. % as direct diffusion source above the ternary transition temperature for GBD processing followed by secondary annealing. The changes in mass gain was analyzed and weighted against the magnetic properties. For the recycled magnet, the coercivity (H$_{Ci}$) values obtained after optimal GBDP yielded ~60% higher than the starting recycled HDDR powder and 17.5% higher than the SPS-ed processed magnets. The fresh MF-15P HDDR Nd-Fe-B based magnets gained 25–36% higher coercivities with Pr-Cu GBDP. The FEG-SEM investigation provided insight on the diffusion depth and EDXS analysis indicated the changes in matrix and intergranular phase composition within the diffusion zone. The mechanism of surface to grain boundary diffusion and the limitations to thorough grain boundary diffusion in the HDDR Nd-Fe-B based bulk magnets were detailed in this study. rare earth permanent magnets HDDR Nd$_2$Fe$_{14}$B recycling spark plasma sintering grain boundary diffusion processing (GBDP) high coercivity redki zemeljski trajni magneti recikliranje sintranje s plazmo postopek difuzije meje zrn (GBDP) visoka magnetna koercivnost true false true Angleški jezik Slovenski jezik Članek v reviji 2022-01-12 10:52:30 2022-01-12 10:52:35 2022-09-13 03:54:49 0000-00-00 00:00:00 2020 0 0 17 str. iss. 16, art. 3528 Vol. 13 Aug. 2020 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 537.6(045) 1996-1944 10.3390/ma13163528 25316867 RAZ_Ikram_Awais_2020.pdf RAZ_Ikram_Awais_2020.pdf 1 923CE48A9AB951F00E6B01B4E51CC271 2d7c22a3f8df0115d90442c11471b9fcd8e674046eb4cb7b2e82dd808cd9da62 b7605b86-738d-11ec-abdb-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=152797 https://www.mdpi.com/1996-1944/13/16/3528 1 30cb536b-738d-11ec-abdb-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=152796 Fakulteta za strojništvo 0 0 0