2025年4月21日，博士生李健同学和青年教师宋欣博士共同完成的论文“Magnetic-field-assisted solute partitioning in 2:17-type Sm-Co-Fe-Fe-Zr magnets towards enhancing coercivity”被Journal of Materials Science & Techonology录用！祝贺他们！

Abstract：

Simultaneously achieving high remanence and high coercivity in hard magnets is highly desired for applications, but is difficult because they are intrinsically trade-off. This work presents magnetic-field-assisted solute partitioning in the pinning-controlled Sm-Co-Fe-CuZr magnets to enhance coercivity without deteriorating remanence. As exhibited in a model commercially-sintered magnet Sm25Co44.9Fe21.5Cu5.6Zr3.0 (wt.%), applying an external magnetic field during post-aging slow cooling process (defined as magnetic slow cooling, MSC) can effectively enhance coercivity Hcj from 18.50 kOe for the magnet with conventional non-MSC processing to 21.30 kOe, well retaining the remanence Br above 11.6 kG. Detailed microstructural and microchemical investigations revealed that MSC accelerates solute partitioning between rhombohedral Sm2Co17 (2:17R) nanocells and hexagonal SmCo5 (1:5H) cell boundaries, by enriching Fe/Co contents inside the former that improves its saturation magnetization and enriching Cu content inside the later that strengthens the pinning force to hinder domain wall motions. In addition, MSC can also effectively reduce the cell-edge 2:17R’ phase (alternatively an incompletely-decomposed product with one faulted basal layer in 2:17R lattice, or an intermediate phase of 2:17R equilibrium phase) that was harmful for both remanence and coercivity. Thermodynamically, the beneficial role played by MSC can be attributed to the associated magnetostatic energy, which provides extra driving force to promote phase transition and solute partitioning. Further study showed that optimizing MSC cooling rate can further enhance Hcj to 23.30 kOe without deteriorating Br, demonstrating that the magnetic-field-assisted solute partitioning method is effective to overcome the remanencecoercivity trade-off in 2:17-type Sm-Co magnets.