Fabrication of low-cost Nd-Fe-B sintered magnets reusing ultrafine powders

摘要

To reduce the cost of Nd-Fe-B sintered magnets, the ultrafine powders recycled during the jet-milling process were added into intergranular regions by blending. The effects of ultrafine powder content on the magnetic properties, thermal stability and microstructure were investigated. It was found that the intrinsic coercivity H_(cj) was significantly improved from 1048 to 1396 kA m~(-1) on increasing the ultrafine powder content to 10wt- percent. Meanwhile, the reversible temperature coefficient beta_H of H_(cj) over the range 20-100 deg C was decreased in the absolute value, indicating that the thermal stability was improved. Moreover, the maximum energy product (BH)_m increased slightly on adding 5 wt- percent ultrafine powder, which can be attributed to the combined effects on the normal coercivity H_(cb) and on the remanent induction B_r.