High‐performance sintered R2Fe14BNx (R=Nd/Pr/Dy) magnets

High‐performance R2Fe14BNx‐type magnets (R=Nd and/or Pr/Dy) were successfully prepared by sintering. The optimum magnetic properties are coercivity iHc: 680–1440 kA/m; Hc: 500–1000 kA/m; Br: 1.0–1.3 T; and (BH)m: 180–250 kJ/m3 depending on the composition and processing parameters, especially the proper sintering conditions, including nitrogen intake at 1040 to 1050 °C. The magnets thus obtained have Tc values of 335 to 370 °C depending on the nitrogen content, which should be <6 at. % for thermal stability. The anisotropy field increases from 6.2 to 8 T with addition of nitrogen, 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 nitrogen, due to the replacement of the Nd‐rich phase at grain boundaries by more corrosion‐ resistant nitrides.