Magnetic, structural and thermal properties of the Finemet-type powders prepared by mechanical alloying

The mechanical alloying process has been used to prepare nanocrystalline Fe73.5Si13.5B9Nb3Cu1 powders in a high energy planetary ball-mill Retsch PM400/2. Morphological, microstructural, structural, thermal and magnetic characterizations of the powders milled several times were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and hysteresis meter. A mixture of Fe(Si)-type nanograins (14nm), Fe2B boride phase (∼12nm), and bcc substitutional Fe(B)-type solid solution is obtained after 150h of milling. The coercivity and saturation magnetization values are about 62Oe and 14emu/g, respectively. Several magnetic transition temperatures are revealed in the DSC scans of the ball-milled powders in the temperature ranges 500–560°C and 599–606°C, related to the Fe(B) and Fe(Si)-type phases, respectively. [Display omitted] ► Nanostructured Fe73.5Si13.5B9Nb3Cu1 Finemet powders were prepared by MA. ► Analysis of the XRD patterns by using the Rietveld refinement. ► The formation of Fe2B boride, Fe(B)-type and Fe(Si)-type solid solutions are achieved after 150h of milling. ► Several magnetic temperature transitions are revealed in the DSC scans. ► The distribution of Si, B and Nb atoms in the Fe lattice leads to the heterogeneity of the Finemet powders.