CHANGES OF STRUCTURE AND MAGNETIC-PROPERTIES FOR A MIXTURE OF ALPHA-FE AND FE3N POWDERS DURING MECHANICAL ALLOYING PROCESS

The X-ray diffraction was used to monitor the structural changes of a mixture of alpha-Fe and Fe3N powders during the ball milling. Changes of saturation magnetization of the powder mixture were also measured. The results showed that Fe3N decomposed quickly and then disappeared w ith increasing milling time, some N atoms soluted in alpha-Fe. After m illing for about 30 h, a stable supersaturated solid solution with N c ontent of about 0.290-0.346 wt% was obtained. The grain size decreased with increasing milling time and reached a constant of about 8 nm aft er about 30 h milling. The saturation magnetization of the powder mixt ure initially decreased, but began to increase when milling time excee ded 5 h, and finally reached a constant value when milling time exceed ed 30 h.