Magnetic properties enhancement of multi-element-doped SmCo7 nanocrystalline alloys

Abstract

TbCu7-type SmCo7-based permanent magnets possess great potential for applications in high-temperature service because of their large magnetocrystalline anisotropy and low temperature coefficient of coercivity. However, the application of SmCo7-based alloys is seriously limited by the trade-off between the TbCu7-type phase stability and the intrinsic magnetic properties, as well as the balance between the saturation magnetization and the coercivity. In this study, a series of SmCo7-based nanocrystalline alloys doped by Mn, Cu, and Fe elements were prepared. The TbCu7-type phase was well stabilized by nanostructuring and appropriate doping. Tailoring the element doping enhanced the coercivity by 50 % and achieved a balance between the saturation magnetization and the coercivity of the SmCo7-based nanocrystalline alloys. The mechanisms of the magnetic properties enhancement were disclosed based on the characterization of microstructures and magnetic structures. It is proposed that a high proportion of the TbCu7-type SmCo7 main phase is critical to achieve excellent magnetic properties. This study provides both the method and rules for the development of multi-component Sm-Co-based alloys with high integrated magnetic properties.