Enhanced magnetic properties and bending strength of hot deformed Nd–Fe–B magnets with Cu additions

Effects of compositions on characteristics and microstructures for melt-spun ribbons and die-upset magnets of Nd12.8+xFe81.2−x−y−zCoyGazB6

“…The circular grain alignment in the excessively Nd-rich alloy is mainly due to the extra Nd-rich grain boundary phase. It is generally known that the texture in the die-upset Nd-Fe-B alloy develops by stress-induced preferential grain growth via dissolution and precipitation [5,7]. The driving force for the stress-induced preferential grain growth is the difference in the strain energy of individual grains under compressive stress, which results from the anisotropic mechanical properties of the Nd 2 Fe 14 B compound.…”

“…Fully dense anisotropic Nd-Fe-B magnets can be produced by melt spinning followed by hot pressing [1][2][3][4][5]. Magnetic properties, especially remanence and maximum energy product of the die-upset magnets, strongly depend on the alignment of the easy c-axis of the grains.…”

Computer simulation of coercivity improvement due to microstructural refinement

“…It has also been reported that coercivity increases with decreasing grain size. 8,9 These observations and calculations suggest that the microstructure plays an important role in the determination of coercivity.…”

Effects of excessive grain growth on the magnetic and mechanical properties of hot-deformed NdFeB magnets

“…Breaking the bonds across grain boundaries to produce intergranular fracture is accompanied by plastic deformation in the grains adjacent to the boundary that fractures. From high-resolution transmission electron microscopy (HRTEM) images, the elongated grain interfaces of HD magnets are mainly of two types: parallel interface and triangle interface, where the trigonal grain boundaries contribute to the increase of fracture strength [14]. So the existence of Nd-rich phase at the grain boundaries plays an important role in determining the mechanical properties of HD NdFeB magnet.…”