FORMATION OF THMN12 STRUCTURE BY HEAT-TREATMENT OF MECHANICALLY ALLOYED ND-FE-TM ALLOYS (TM-EQUIVALENT-TO-TI, V, MO) AND HARD MAGNETIC-PROPERTIES OF THEIR NITRIDES

Mechanical alloying and rapid solidification were applied to prepare permanent magnets of ThMn12-type NdFe12-CTMC nitrides for TM = Ti, V and Mo. ThMn12-type phases formed on subsequent isothermal aging of mechanically alloyed or rapidly solidified Nd-Fe-TM materials except for TM = Ti. The NdFe10Mo2Nx compound was obtained on nitrogenation at 823 K for 3.6 ks in an atmosphere of flowing N2 gas, whereas the NdFe10V2Nx compound did not form under this nitriding condition. Nitrogenation of NdFe10Mo2 produced by mechanical alloying and,aging converted the soft magnetic parent compound into the nitride with hard magnetic properties of coercivities up to 512 kA m-1. Such powder was suggested to be applicable as a starting material for resin-bonded magnets.