The microstructure and magnetic properties of nanocrystalline Fe100-xSix alloys

Nanocrystalline Fe100-xSix (x less than or equal to 25) alloys have been prepared by mechanical alloying. The crystallite size of the nanocrystalline FeSi alloys is about ten to fifteen nm. The individual crystallite separated by disordered grain boundaries has the structure of b.c.c. alpha-Fe. The Mossbauer patterns show that substitution of Si atoms for Fe ones is almost disordered in the nanocrystalline FeSi alloys. The saturation magnetization of the nanocrystalline FeSi alloys is slightly less than that of single-crystalline and polycrystalline FeSi alloys, whereas their coercive force and effective magnetocrystalline anisotropy constant are higher than those of the corresponding single-crystalline and polycrystalline FeSi alloys. The much higher coercive force and higher effective anisotropy of the nanocrystalline FeSi alloys may be related to the high strain in the grain boundaries.