High-Performance Sintered R sub 2 Fe sub 14 BN sub x (R = Nd/Pr /Dy) Magnets

High-performance R sub 2 Fe sub 14 BN sub x -type magnets (R = Nd and/or Pr/Dy) were successfully prepared by sintering. The optimum magnetic properties are coercivity sub i H sub c : 680-1440 kA/m; H sub c : 500-1000 kA/m; B sub r : 1.0-1.3 T; and (BH) sub m : 180-250 kJ/m exp 3 depending on the composition and processing parameters, especially the proper sintering conditions, including nitrogen intake at 1040-1050 deg C. The magnets thus obtained have T sub c values of 335-370 deg C depending on the N content, which should be < 6 at.% for thermal stability. The anisotropy field increases from 6.2 to 8 T with addition of N, and magnetization measured at 2 T increases by 18%. The weight loss after immersion in a 5% HCL solution for 30 min is 25% less for nitrogenated magnets than for those without N, due to the replacement of the Nd-rich phase at grain boundaries by more corrosion-resistant nitrides. Graphs.