Effects of the substitution of Cu or Nb for Fe on the structure and magnetic properties of Nd8Fe84Ti8 alloys prepared by mechanical alloying

The effects of a partial substitution of Cu or Nb for Fe on the structure a nd magnetic properties of mechanically alloyed Nd8Fe84Ti8 alloys were studi ed. Compared with Nd8Fe84Ti8 alloys prepared under the same conditions, the temperature necessary for the formation of the Nd(Fe, Ti)(12) phase decrea ses from 900 to 750 degrees C with the addition of 3 at. % Cu. The addition of Cu hinders the nitrogenation of the Nd(Fe, Ti)(12) phase. The pretreatm ent of hydrogenation on the Cu-added alloys at 300 degrees C facilitates th e formation of nitrides. With increasing annealing temperature, the intrins ic coercivity of the nitrides increases until it attains a maximum at 850 d egrees C. The addition of Nb is harmful to the formation of the perfect Nd( Fe, Ti)(12) phase. For the 3 at. % Nb-containing alloys, annealing at 960 d egrees C makes a metastable phase Nd(Fe, Ti)(7) be formed. The addition of Nb is unfavorable for the intrinsic coercivity and the maximum magnetic ene rgy product of the nitrides. (C) 2000 American Institute of Physics. [S0021 -8979(00)90708-4].