Optimization of Electromagnetic Wave Absorption Properties in Sm₂Fe₁₇ Alloys via Compositional Design and Particle Size Control

In this study, a series of Sm₂Fe₁₇ alloy powders were successfully synthesized via the reduction-diffusion method. The synergistic regulatory mechanisms of the Sm/Fe stoichiometric ratio and particle size on the microstructure and microwave absorption performance were systematically investigated. Electromagnetic parameter measurements revealed that the system is dominated by magnetic loss. Specifically, the Sm₂Fe₁₇-4 sample exhibited the strongest magnetic loss capability due to defect effects induced by lattice distortion. However, limited by impedance mismatch, the frequency of its peak absorption was offset from that of the maximum effective absorption bandwidth. By introducing airflow milling classification, the lattice strain was effectively released. The reduction in particle size significantly increased the coercivity and anisotropy field, thereby shifting the absorption bands toward higher frequencies. Notably, the sample treated at 4500 rpm achieved full coverage of the Ku-band and demonstrated superior impedance matching characteristics. The synergistic strategy combining "compositional regulation" and "particle size optimization" proposed in this work effectively overcame the mutually exclusive trade-off between "strong absorption" and "broad bandwidth" under single-variable regulation. This study provides important theoretical and experimental foundations for designing novel rare-earth-based high-frequency microwave absorbing materials.