Fabrication and characterization of Fe16N2 micro-flake powders and their extrusion-based 3D printing into permanent magnet form

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Official URL: https://dx.doi.org/10.1002/adem.202000311

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.