Anisotropic bonded magnets fabricated via surfactant-assisted ball milling and magnetic-field processing

Abstract

Anisotropic bonded magnets are fabricated by surfactant-assisted ball milling in a magnetic field and magnetic field alignment of the milled chip-like nanoparticles of the Sm-Co and Nd-Fe-B materials. It is found that the application of magnetic fields during the ball milling strengthens the anisotropy of the chips and therefore improves the alignment. For SmCo 5 phase-based chips, for instance, energy products up to 26.0 MG Oe and 19.1 MG Oe are obtained for the chips and the bonded magnets, respectively. This combined technique opens a new approach to the fabrication of anisotropic bonded magnets for various applications.

Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets

“…The microstructure (Figure 2) consists of predominantly equiaxed grains, so the exact fracture behavior of the melt spun ribbon is not clear. This is in contrast to surfactant-assisted milling studies in other systems, which produced distinct nanoparticles after similar times [12][13][14][15][16]. …”

“…The surfactant eliminates re-welding of fractured particles that occurs during dry milling. This consequently leads to a reduction in particle size [12][13][14][15][16]. Figure 9 shows X-ray diffraction patterns of the surfactant-assisted milled samples.…”

Preparation of an α″‐Fe16N2 Magnet via a Ball Milling and Shock Compaction Approach

“…For ball milling approaches used to prepare other permanent magnets, [18,[21][22][23] the sample is cold welded because the crushed fine particles have a fresh surface, which is easily welded during the ball milling process. [18] Cold welding should be avoided to obtain fine particles.…”

“…[18,[21][22][23] Milling magnetic raw materials into nanocomposites in flake shape, which can be used for bonded magnets, has the advantage of controlling both size and shape. Several groups have tried to prepare a 00 -Fe 16 N 2 by the ball milling method.…”

Bulk anisotropic nanocrystalline SmCo6.6Ti0.4 permanent magnets

“…1). Compared with the non-aligned sample, the intensity of the (0 0 2) diffraction peak of the magnetically aligned sample was much stronger, indicating that there is a crystallographic [0 0 1] texture in the as-milled powder sample [15], as shown in Figure 1a. The SEM images of the as-milled SmCo 6.6 Ti 0.4 powder is shown in Figure 1b, where it can be seen that the powder consists of thin flakes with the thickness of $200 nm, while the length is in the range of 1-20 lm.…”