Aging Treatment to Enhance Coercivity Through Grain Boundary Modification in SmFe10V2 Bulk Magnets

We explored the potential for an aging treatment to achieve high coercivity, of 0.859 MA/m, in a SmFe10V2 alloy with a ThMn12-type structure. Bulk magnets were fabricated by sintering ball-milled powders, followed by aging treatment. XRD and SEM analyses revealed that aging treatment promotes the formation of a Sm-rich grain boundary phase with nano-scale thickness. The high Sm content (~60–80 at.%) and low Fe content (~20–30 at.%) in the grain boundary phase led to non-ferromagnetism, enhancing the coercivity by isolating the 1–12 grains and weakening the dipolar interaction between the grains. The aging temperature and duration were optimized to maximize the Sm-rich phase and minimize the soft magnetic SmFe2 phase. This study provides a new fabrication method for ThMn12-type magnets and investigates the relationship between microstructure and coercivity, offering valuable insights for the future design and development of high-performance SmFe12-based magnets.