Hot Deformation
Net-shape Processing of nanocrystalline Nd–Fe–B magnets

Due to the low melting point of the Nd-rich phase, Nd-Fe-B melt spun ribbons can be hot-compacted in order to produce isotropic fully dense green compacts with nanocrystalline structure. A subsequent die-upsetting or backward-extrusion process is applied to prepare uniaxial or radial textured tablets and ring magnets with energy densities above 300 kJ/m³, respectively [1].

The unique equipment available in our group enables production of near-net-shape radially textured ring magnets by backward-extrusion. The main part of the ring shows overall good alignment of flakes and nano-grains with flat surfaces parallel to pressing direction.

If hot-compacted precursors are prepared with such a height and diameter that at the end of hot-deformation (desired degree of deformation is obtained) material completely fills the cavity, die-upsetting results in crack-free, mechanically and magnetically homogenous, highly-textured tablet magnets.

[1] I. Dirba, S. Sawatzki, and O. Gutfleisch, Net-shape and crack-free production of Nd-Fe-B magnets by hot deformation, J. Alloy. Compd. 589 (2014) 301-306.
DOI: j.jallcom.2013.11.188