Iron-alumina nanocomposites prepared by ball milling

Small magnetic particles of iron embedded in an insulating alumina matrix have been prepared by ball milling, either by direct milling of a mixture of iron and alumina powders or indirectly by ball-milling enhanced displacement reaction between magnetite and aluminum metal. The average particle size could be reduced to the 10-nm range as indicated by X-ray diffraction linewidths and SEM (scanning electron microscopy). The change in the saturation magnetization and the coercivity relates to the change of the phase composition, decrease of the particle size, and accumulation of internal stresses.>