Rare‐Earth‐Free Iron‐Based Permanent Magnets: Progress, Challenges, and Perspectives

ABSTRACT Growing demand for secure, sustainable, and affordable magnetic materials has drawn significant attention to rare‐earth‐free Fe‐based permanent magnets. This review integrates recent advances from atomic‐scale theory to bulk processing. We first outline the fundamental parameters that govern permanent‐magnet performance, such as saturation magnetization ( M s ), magnetocrystalline anisotropy, Curie temperature ( T c ), and microstructural factors. We then survey four principal material families. The first is Fe–Co alloys whose anisotropy is enhanced through lattice strain and light‐element doping. The second is chemically ordered Fe–Ni, tetrataenite, originally discovered in meteorites. The third is nitrogen‐rich iron phases typified by α″‐Fe 16 N 2 . The fourth is iron phosphides and borides such as Fe 2 P and Fe–B. Although calculations predict outstanding magnetic strength, experimental results remain limited by phase instability, grain‐size effects, and processing constraints. To bridge this gap, we highlight four complementary research directions: strain engineering, heteroatom doping, deliberate microstructure control, and data‐driven ab initio calculations. Coordinated progress in these areas could yield Fe‐based magnets with high coercivity and robust magnetization, enabling practical devices for electrified transport, renewable‐energy conversion, and compact electronics without costly rare‐earth elements.