High-coercivity SmFe₁₀V₂ powder with Sm-rich layers prepared by a reduction-diffusion process

The remarkable intrinsic hard magnetic properties of SmFe₁₂-based powders are difficult to transform into extrinsic properties for practical applications; in particular, the coercivity is insufficient because the conventional magnetic isolation structure, which relies on nonmagnetic intergranular phases and is critical for inducing high coercivity in commercial Nd₂Fe₁₄B systems, has not yet been perfected. In this study, we present a new approach for achieving magnetic isolation with a reduction-diffusion process that endows SmFe₁₀V₂ powder with nonmagnetic Sm-rich layers. The optimal sample of this Sm-rich layer surrounding SmFe₁₀V₂ powder has a high coercivity of 744.9 kA/m and a moderate maximum magnetization of 61.7 Am²/kg. Based on phase characterization and microstructure observation, the principal SmFe₁₀V₂ magnetic phase is well maintained, and the surrounding Sm-rich layers separate the magnetic phases, weakening the ferromagnetic interaction of neighboring magnetic phases and contributing to the high coercivity. Our study presents a new method for developing high-coercivity magnetic powders by introducing nonmagnetic layers.