Preparation of nanocrystalline Fe-Si alloys and their magnetic properties

Nanocrystalline Fe-Si alloys have been prepared using the mechanical alloying method. The structure of the obtained Fe-Si alloys is the same as that of bcc alpha-Fe. The final powders obtained mainly consist of particles with a grain size of from a few hundred nanometers to several microns, and the particles are composed of subgrains with a microcrystalline size of about 15-20 nm and an almost completely random orientation with respect to each other. The magnetic properties have also been investigated. The specific saturation magnetization (sigma(s)) values are slightly less than those of the corresponding single-crystalline and polycrystalline Fe-Si alloys, while the coercive force (H-c) values are much higher than those of the corresponding bulk Fe-Si alloys, The magnetic spectra are all relaxation-type except for Fe75Si25; the values of mu' and mu '' are comparable to those of ferrite composite materials and domain wall displacements are predominant in the magnetization process.