Microstructure and magnetic properties of NdFeB magnets fabricated by current-applied pressure-assisted process

The microstructure and magnetic properties of isotropic and anisotropic NdFeB magnets fabricated by current-applied pressure-assisted (CAPA) process has been investigated. The process consists of CA-press to make full dense isotropic magnets and CA-deformation to obtain high energy anisotropic magnets. During the CA-press, the increase of applied pressure is found to suppress grain growth and to lead high coercivity, while the increase of applied current deteriorates coercivity. Through the CA-deformation process, the platelet grains with c-axis texture parallel to press direction are formed. The best properties of CA-deformed magnets obtained from MQP-A powder were Br = 1.36 T (13.6 kG), ic = 868 kA/m (10.9 kOe) and (BH)max = 352 kJ/m3 (44.2 MGOe). And, from MQU-G powder were Br = 1.31 T (13.1 kG), iHc = 1457 kA/m (18.3 kOe) and (BH)max = 333 kJ/m3 (41.8 MGOe).