NITROGENATED 1/12 COMPOUNDS PREPARED BY MECHANICAL ALLOYING

Nd(FeM)12 compounds with M=Mo,Ti,V prepared by mechanical alloying were nitrogenated using the gas phase interstitial modification process. The Nd(FeM)12 structure has been found to be stable after nitrogenation at around 650-degrees-C, but with increased lattice parameters. The change in unit cell volume, DELTA-V/V, is larger in mechanically alloyed powders than in as-cast alloy powders. The change of Curie temperature upon nitrogenation is almost the same, DELTA-T(c)/T(c) almost-equal-to 30%, for the three compounds studied. The mechanically alloyed powders and metal-bonded magnets with the ThMn12 crystal structure show interesting hard magnetic properties with a coercivity H(c) = 7-10 kOe. The average grain size of the mechanically alloyed powders with the highest coercivity was about 4000 angstrom.