Some Introduction of Fe16N2 Compound

The regular non-rare earth permanent magnets can be classified into four types:

1. Quench hardening type, include carbon steel, tungsten steel, chromium steel, cobalt steel and aluminum steel. The coercivity will be obtained byhigh temperature quenching.
2. Precipitation hardening type, include FeCualloy, FeCo alloy and Alnico alloy.
3. Age hardening type.
4. Ordered hardening, include AgCuAl, Fe(Co)Pt and manganese-based alloy.

Fe-based magnetic compounds generally have high Curie temperature and saturation magnetization. However, magnetic anisotropy of these compounds relatively low. Their combination magnetic properties can be improved through alloying technology. Typically, magnetic performance of transition metal’s ferromagnetic compound probably be enhanced by permeating nitrogen atoms to the crystal lattice to form transition metal nitrides. Atomic distance between transition metal has been changed due to interstitial nitrogen atoms, hence influenced saturation magnetization, magneto crystalline anisotropy and Curie temperature.

The only commercial nitride permanent magnet material is SmFeN magnet. For SmFeN magnet, nitrogen atoms in the lattice changed Fe-Fe distance, thus improved Curie temperature and uniaxial magneto crystalline anisotropy. The content of interstitial nitrogen atoms is not stable during sintering process, and Sm₂Fe₁₇N₃ will be decomposed into α-Fe and SmN phase below sintering temperature, therefore, sintered magnet can’t be fabricated by SmFeN power.

Fe₁₆N₂ is regarded as another candidate material of high energy product non-rare earth permanent magnet relies on its giant Ms and magneto crystalline anisotropy. As a kind of metastable compound, Fe₁₆N₂ is very hard to fabricate high coercivity block material, and Fe₁₆N₂ permanent magnet still cannot be prepared in quantity. Excellent microstructure will provide suitable grain size and boundary, and give enough coercivity to magnet. The grain size and boundary of Fe₁₆N₂ cannot be regulated through traditional methods.