High-performance critical-element-free permanent magnets

Hysteresis curves of L10 FeNi-based alloys.
Hysteresis curves of L10 FeNi-based alloys.

CMI scientists at Ames Laboratory conducted this research.

Achievement

Demonstrated that mechanochemical preprocessing (MP) is beneficial for nitrogen insertion/topotactic extraction. Achieved effective 98+% yields of ordered t-FeNiN (precursor phase to L10 FeNi) and 1.2 kOe coercivity (comparable to Alnico) in Ni-rich L10 phase Fe45Ni55. 

Significance and impact

Achievement of significant coercivity important step towards high-performance, rare earth-free, low-cost magnet

Next steps

Quantitative topotactic extraction at T << 250 °C to yield 95-98% yield of L10-FeNi, followed by scale-up to ~1 – 10 g quantities of L10-FeNi, IP disclosure, and the synthesis of permanent magnets

XRD patterns showing AlCl3 as the optimal process control agent for formation of the FeNiN precursor phase.
XRD patterns showing AlCl3 as the optimal process control agent for formation of the FeNiN precursor phase.