Anisotropic Nd–Fe–B nanocrystalline magnets processed by spark plasma sintering and in situ hot pressing of hydrogenation–decomposition–desorption–recombination powder

Coercivity enhancement of HDDR-processed Nd–Fe–B permanent magnet with the rapid hot-press consolidation process

“…Such a phenomenon has not been reported in previous studies using the conventional hot-press [8,[14][15][16] or the SPS apparatus [10,11]. Moreover, a high H cJ surpassing that of the initial HDDR powder by 25% has been obtained with this process.…”

“…Morimoto et al [9] reported improved alignment in the final bulk magnet by hot pressing the powder at an incomplete hydrogen-desorption stage, but the coercivity of the product was somewhat lower. More recently, the spark plasma sintering (SPS) technique that enables sintering at a reduced temperature was employed [10], and improvement in the c-axis texture was demonstrated by post-sintering hot deformation [11]. However, detailed investigations of the microstructural variations and their influence on intrinsic coercivity (H cJ ) during the consolidation process were not conducted in previous investigations.…”

Coercivity of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering method

“…Recently, hot-deformed magnets have been successfully produced by the spark plasma sintering (SPS) method. [15][16][17][18][19] However, the magnetic properties of these Nd-Fe-B hot-deformed magnets produced by the SPS method are not yet comparable to those of Nd-Fe-B sintered magnets. In order to improve the magnetic properties of Nd-Fe-B hot-deformed magnets, it is necessary to improve their coercivity by the addition of Nd-Cu alloy.…”

Magnetic Properties of Nd-Fe-B Anisotropic Magnets Prepared by Spark Plasma Sintering Method

“…Using the SPS method, powder can be easily consolidated at relatively lower temperatures in a short consolidation time. This method has been used in several studies to consolidate Nd-Fe-B powders [11][12][13][14][15][16] , and may also be applicable to the production of hot-deformed magnets 17) . It is known that the magnetic properties of Nd-Fe-B magnets depend on the degree of crystallographic alignment of the tetragonal Nd 2 Fe 14 B magnetic phase.…”