Anisotropic nanostructured magnets by magnetic-field-assisted processing

It has been a great challenge to produce anisotropic nanocrystalline bulk magnets. In this paper, we report our recent work in preparing anisotropic bonded magnets consisting of SmCo(5) nanocrystalline particles. The work involved synthesis of nanocrystalline hard magnetic SmCo(5) particles by ball milling in the presence of a magnetic field. Structural and magnetic characterizations show the alignment of the c-axis of the SmCo(5) grains upon the magnetic-field-assisted ball milling, while the grain size was controlled under 15 nm. The formation of the texture may be attributed to the effect of magnetic fields on the grain orientation during the cold welding process during ball milling. The as-milled particles were then compacted under a magnetic field with a binder to form bonded bulk SmCo(5) nanostructured magnets. X-ray diffraction patterns show c-axis alignment in the bulk magnets, which was consistent with the magnetic measurements. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3337656]