Consolidation of cobalt nanorods: A new route for rare-earth free nanostructured permanent magnets

Semih Ener (1) , Evangelia Anagnostopoulou (2) , Imants Dirba (1) , Lise-Marie Lacroix (2) , Frédéric Ott (3) , Thomas Blon (2) , Jean-Yves Piquemal (4) , Konstantin P Skokov (1) , Oliver Gutfleisch (1) , G. Viau (2)

1 TU Darmstadt - Technische Universität Darmstadt - Technical University of Darmstadt
2 LPCNO - Laboratoire de physique et chimie des nano-objets
3 LLB - UMR 12 - Laboratoire Léon Brillouin
4 ITODYS (UMR_7086) - Interfaces, Traitements, Organisation et Dynamique des Systèmes

Rare-earth free permanent magnets were produced by consolidation of cobalt nanorods synthesized by the polyol process exhibiting a mean diameter in the range 10e30 nm. Compactions of magnetically prealigned rod assemblies at various pressures and temperatures were carried out to make dense materials. Bulk magnets exhibiting a very good mechanical strength and an energy product as high as 65 kJ m À3 were obtained. The best results were obtained when the compaction conditions were soft enough to preserve the morphology and alignment of the rods in the final material, as revealed by X-ray diffraction and neutron scattering. For the first time the bottom-up approach is convincingly reported to produce bulk magnets without the addition of any matrix, the obtained nanostructured materials exhibit coercivity much higher than the AlNiCo magnets and can fill the performance " gap " between hexaferrites and rare-earth based magnets.

Mots clés: Permanent magnets; Bottom-up; Cobalt nanorods; Energy product; Consolidation process

Domaines: Matériaux

Semih Ener, Evangelia Anagnostopoulou, Imants Dirba, Lise-Marie Lacroix, Frédéric Ott, et al.. Consolidation of cobalt nanorods: A new route for rare-earth free nanostructured permanent magnets. Acta Materialia, 2018, 145, pp.290-297. ⟨10.1016/j.actamat.2017.12.009⟩. ⟨hal-01982212v2⟩