Desorption-recombination behavior of as-disproportionated NdFeCoB compacts by reactive deformation

The disproportionated phases of Nd Hx, Fe2B,and a-Fe from Nd2Fe14B were applied to prepare Nd Fe B magnets by two different routes. The results show that the route of annealing in horizontal vacuum sintering furnace cannot reach the purpose of complete recombination after the hot pressing and hot deformation process due to the lack of dehydrogenation channel. The route of applying low pressure of 4–25 MPa on the as-disproportionated green compact during the desorption recombination process in situ hot deformation in a spark plasma sintering(SPS)system can obtain completely recombined Nd Fe B magnet with good anisotropy and magnetic properties. The maximum magnetic properties,(BH)max= 201 kJ m-3,Br= 1.142 T and Hcj= 469 k A m-1, are obtained after being treated for 15 min at 750 °C under low pressure.