Novel permanent magnet based on highly anisotropic TbCu7-type compounds

CMI researchers at Ames National Laboratory conducted the research for this highlight

Innovation
SmFe7Nx-based hard permanent magnets can be reliably synthesized and consolidated via a mechanochemically-assisted approach.

Achievement
Nitrogenation and sintering of fine, highly crystalline SmFe7 powders yields a bulk permanent magnet with a high relative density of 82%. The magnet has a maximum energy product of BHmax = 11.0 MGOe and coercivity of Hc = 28.6 kOe, both substantial improvements relative to unconsolidated powders.

Significance and Impact

  • Cost and criticality: Non-critical, abundant and inexpensive materials like Fe and Sm with additions of La and Ce to improve thermal stability.
  • Potential competitor of Nd-based permanent magnets with comparable or better properties.

Hub Goal Addressed
The use of critical rare-earths (Nd, Dy) is reduced through development and deployment of novel permanent magnets based on TbCu7-type materials.

Hysteresis loops of as-synthesized SmFe7Nx powder (green curve) and a bulk magnet obtained after consolidation at 420 °C that resulted in a record high 82% relative density (red curve)
Hysteresis loops of as-synthesized SmFe7Nx powder (green curve) and a bulk magnet obtained after consolidation at 420 °C that resulted in a record high 82% relative density (red curve)