Preparation of an α″-Fe₁₆N₂ Magnet via a Ball Milling and Shock Compaction Approach

α″-Fe₁₆N₂ has been suggested as a promising candidate for future rare-earth-free magnets. In this paper, a unique technical route including a ball milling approach and shock compaction is experimentally demonstrated as a promising way to produce an α″-Fe₁₆N₂ magnet. Firstly, α″-Fe₁₆N₂ powder is prepared by ball milling, in which ammonium nitrate (NH₄NO₃) is adopted as a solid nitrogen source. The volume ratio of the α″-Fe₁₆N₂ phase reaches 70% after 60 h of milling with a ball mill rotation speed of 600 rpm in planetary mode. Its saturation magnetization (M_s) is 210 emu g^–1 and the coercivity is 854 Oe at room temperature. After ball milling, shock compaction is used to compact the milled powder sample into a bulk magnet. Its magnetic properties and crystalline structure are characterized. Overall, the ball milling-based approach can be used to prepare α″-Fe₁₆N₂ magnets at an industrial production level.