Novel high-coercivity Fe_16-xAl_xN₂ alloy

Iron nitrides (Fe₁₆N₂) have recently attracted considerable attentions for the future rare-earth (RE) free permanent magnets due to its low cost and high magnetization compared to other RE-free magnetic materials. Despite such a high remanent magnetization, its usefulness is restricted because it is easily de-magnetized. Here, using the first-principles density functional theory calculations, we extensively investigated the structure evolution, stability and magnetic properties of Fe_16-xAl_xN₂ alloys by varying Al contents. We find that substituting Fe by Al in Fe₁₆N₂ greatly improves the magnetic anisotropy of the alloys, and their coercivities can increase by about 300%compared to that ofFe₁₆N₂. We thus expect that these Fe_16-xAl_xN₂ alloys will be promising candidates for strong rare-earth free permanent magnets.