Coercivity enhancement in (Ce,Nd)-Fe-B sintered magnets prepared by adding NdHx powders

(Ce,Nd)-Fe-B sintered magnets were prepared by the addition of NdHx powders in Ce9Nd4.5Fe80B6.5 powders. The coercivity is rather low in Ce9Nd4.5Fe80B6.5 magnets, and Ce element prefers to distribute at the outer-layer of main phase (Ce,Nd)2Fe14B. The investigation of scanning electron microscope shows that the addition of NdHx powders leads to the increase of Nd content at grain outer-layer of main phase owing to the element diffusion. Magnetization reversal undergoes the nucleation of reversed domain wall at grain outer-later, and the addition of NdHx powders leads to the increase in the nucleation field of reversed domain, giving rise to the significant improvement of coercivity. The larger amount addition of NdHx powders leads to the increase in the amount of intergranular phase, resulting in the decreases of the remanence, the squareness of demagnetization curve and the maximum energy product.