STRUCTURE AND MAGNETIC-PROPERTIES OF SM-2(FE,MN)(17)N-X COARSE POWDERS WITH HIGH COERCIVITY

The influence of a substitution of Mn for Fe in the Sm-2(Fe,Mn)(17)N-x alloys on the structure and the magnetic properties was studied. Sm-2 (Fe,Mn)(17)N-x alloy powders of 32-74 mu m in particle size with sever al values of x were successively synthesized using NH3+H-2 gas. It was found that the primary phase of the powders maintained the Th2Zn17-ty pe structure in the wide range for 0<x<6. On the other hand, the coerc ivity of the powders remarkably increased for x>3. The Sm-2(Fe0.95Mn0. 05)(17)N-5 powder proved to have a coercivity of 0.62 MA/m (7.7 kOe), without a fine grinding. Microstructural analysis by transmission elec tron microscopy and energy-dispersive x-ray analysis revealed the powd er consisted of Sm-7(Fe,Mn)(17)N-3 nanocrystalline grains of 10-30 nm in diameter surrounded by Mn-enriched amorphous phase. (C) 1997 Americ an Institute of Physics.