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

Abstract

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.