Relation between the nanostructures and the magnetic properties of melt-spun Nd-Ce-Fe-B ribbon

Abstract

Sintered Nd-Fe-B magnets are widely used as key components in electric vehicle motors, wind power generators, hard disk drives, and magnetic sensors. To enhance their properties, various processing techniques have been explored. Among these, the melt-spinning process has gained attention for its ability to rapidly quench molten alloys into amorphous or fine nanocrystalline structures. This method produces melt-spun ribbons with significantly finer grain sizes than those obtained through conventional casting, contributing to improved magnetic properties in the final sintered magnets. Grain size is a critical factor in determining magnetic performance. When the grain size approaches that of a single magnetic domain, multi-domain formation is suppressed, leading to enhanced coercivity and overall magnetic performance. In this study, the melt-spinning process is employed to achieve a fine-grained microstructure, while Spark Plasma Sintering (SPS) is used to suppress grain growth during consolidation at relatively low temperatures, thereby preserving the advantages of the melt-spun ribbons. Furthermore, a hot-deformation process is applied to improve crystallographic alignment in the pre-sintered magnets, further enhancing their magnetic properties. This study aims to investigate the crystal structure of melt-spun ribbons under various processing parameters, as well as the magnetic characteristics of sintered magnets fabricated from these ribbons. Both structural and magnetic properties of the melt-spun ribbons and the sintered magnets are systematically analyzed.