Anisotropic HDDR-treated Nd2Fe14B-type powder

Effects of the wheel speeds v and disproportionation time during the SC-HDDR process on the properties of Nd-Fe-B magnetic powders are investigated. It is found that the remanence B r , coercivity H cj and energy products ( BH ) max of magnetic powders all first increase to the maximum at v =3 m/s, and then decrease with enhancing v . This is attributed to the fact that the SC alloy flakes prepared by the wheel speed of 3 m/s display the optimized microstructure. This optimized SC alloy flakes without homogenizing treatment which carried out a short duration disproportionation treatment can prepare the evidently anisotropic powders. With prolonging disproportionation time, the alignment degree of anisotropy of magnetic powders gradually decreases. This is due to the fact that a short duration disproportionation reaction is beneficial to the disproportionated microstructure displaying the lamella crystals, and the lamella disproportionated microstructure is helpful to the formation of anisotropy. Our results confirm that the anisotropic HDDR Nd-Fe-B magnetic powders prepared directly from the SC alloy flakes without homogenizing treatment can be obtained.