STRUCTURE AND MAGNETIC-PROPERTIES OF MECHANICALLY ALLOYED ND(FE,V)(12)N-X COMPOUNDS

The structure and magnetic properties of Nd(Fe,M)(12)N-x (M=Ti,Mo,V) c ompounds prepared by mechanical alloying (MA) have been studied using x-ray diffraction and magnetic measurements. It is found that after an nealing, single-phase Nd(Fe,V)(12) compounds can be obtained over a la rge composition range, but can only be obtained in Nd(Fe,V)(11) after MA. The crystallization of stoichiometric compounds at 750-950 degrees C always produces a small amount of alpha-Fe(V) in addition to the 1: 12 phase. Below 750 degrees C, the crystallization is not complete and large amounts of alpha-Fe(V) are present. When nitriding at 450 degre es C, the alpha-Fe(V) phase disappears accompanied by the formation of an amorphous phase and a 1:7 nitride phase. The crystallized phase re tains the 1:12 structure when nitriding at 480 degrees C. The highest coercivity of 8.8 kOe has been obtained for the NdFe10.5V1.5Nx compoun d. The difference between the coercivities of MA Nd(Fe,V)(12)N-x, Nd(F e,Mo)(12)N-x, NdFe11TiNx, and Sm2Fe17Nx compounds is attributed to the ir different crystallization behavior and phase stability during nitro genation. (C) 1996 American Institute of Physics.