Fabrication and Characterization of Fe₁₆N₂ Micro-Flake Powders and Their Extrusion-Based 3D Printing into Permanent Magnet Form

Fe₁₆N₂ is a compound with giant saturation magnetization approaching or exceeding that of rare-earth-based permanent magnets. The abundance of its elements and low-cost synthesis of this compound has made it highly attractive to replace rare-earth-based permanent magnets that are becoming ever more expensive to utilize in applications. Herein, its synthesis from Fe flakes by surfactant-assisted high energy ball milling is demonstrated. The synthesized Fe flakes are then reduced under forming gas (Ar/H₂), followed by nitridation at low temperatures under ammonia (NH₃) gas. The formation of Fe₁₆N₂ phase exceeding 50% by volumetric fraction is observed and confirmed by X-ray diffraction and Mössbauer analysis. Following the Fe₁₆N₂ flake synthesis, extrusion-based 3D printing is used to check the feasibility of incorporation of the flakes into functional polymer matrix composites. For this purpose, an ink of intermixed synthesized powder with photoresist SU8 is used. Using the prescribed method, a prototype Fe₁₆N₂ permanent magnet composite is successfully produced using an additive manufacturing approach. Such efficient production of Fe₁₆N₂ powders via routes already applicable to magnet production and the consolidation of the powders with 3D printing are expected to open up new possibilities for next-generation permanent magnet applications.