Pr-modified microstructure enhances coercivity in Sm2Co17-type magnets

Optimizing components of the cellular structure is a strategy to enhance the magnetic performance of Sm2Co17type magnets. In this study, Pr is used to modify the cellular structure in Sm2Co17-type magnets, achieving synergistic optimization of coercivity from 32.12 kOe to 34.71 kOe and remanence from 11.23 kGs to 11.36 kGs. Analyses reveal that the increased remanence is attributed to the enhanced saturation magnetization and better grain alignment in the Pr-5 magnet. The incomplete cellular structures and Cu-lean region near grain boundaries are ameliorated in the Pr-5 magnets. Meanwhile, the Pr-modified and Cu-enriched cellular boundary phase, which has a lower magnetocrystalline anisotropy field, enhances the pinning strength of the domain-wall and contributes to the increase in coercivity. The substitution of Pr for Sm has a lower substitution energy in SmCo5 than in Sm2Co17, leading to the slight enrichment of Pr in the 1:5H phase. However, excessive Pr leads to increased amounts of oxides and deteriorates magnetic properties. This work provides valuable insights into developing high-performance Sm2Co17-type magnets by optimizing the microstructure and microchemical components.