Influence of dynamic crystallization on exchange-coupled NdFeB nanocrystalline permanent magnets

Dynamic crystallization was introduced to improve the magnetic properties of NdFeB nanocrystalline permanent magnets by optimizing microstructure. The microstructure was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It has been determined that, compared with the conventional heat treatment, dynamic crystallization can shorten the crystallization time. Moreover, dynamic crystallization can refine grains, enhance the exchange-coupled interaction among grains, and promote the magnetic properties. As a result, the optimal magnetic properties of Nd-10.5(FeCoZr)(83.4)B-6.1(B-r = 0.685 T, H-ci = 732 kA center dot m(-1), H-cb = 429 kA center dot m(-1), (BH)(m) = 75 kJ center dot m(-3)) are obtained after dynamic crystallization heat treatment at 700 degrees C for 10 min.