High-performance critical-element-free permanent magnets

Hysteresis loops (top) for L10 FeNi as synthesized (black) and treated with concentrated HCl (red), demonstrating enhanced remanence and coercivity; bottom panel shows exceptional temperature dependence of coercivities in FeNi (red).
 Hysteresis loops (top) for L10 FeNi as synthesized (black) and treated with concentrated HCl (red), demonstrating enhanced remanence and coercivity; bottom panel shows exceptional temperature dependence of coercivities in FeNi (red).

CMI researchers at Ames Laboratory conducted the research for this highlight

Achievement
Demonstrated enhanced magnetic properties of L10-FeNi by implementing a simple post-synthesis HCl leaching treatment (top). Coercivity exceeds that of Alnico and will likely exceed that of NdFeB above ~150 °C (bottom).

Significance and impact

  • Excellent temperature dependence of coercivity may position magnet, upon optimization, as lower-cost competitor to Alnico.
  • High-performance, rare earth-free, low-cost material with the potential to quickly and broadly penetrate PM markets

Details and next steps

  • Leaching removes paramagnetic impurities and improves microstructure.
  • Plan to scale-up to 1-10 g quantities of the product; IP disclosure drafted.
  • Beneficiation (Fe/Ni ratio; doping with 1-2 at.% of transition elements, optimization of post-synthesis treatment).