Nd-Fe-B Powder Coating for Higher-Coercivity Sintered Magnets

The patent applies local quality by concentrating heavy rare earth elements specifically at the grain boundaries through diffusion processes, rather than uniformly distributing them throughout the alloy. This localized approach enhances coercivity at the grain boundaries where it is most needed, while minimizing the overall amount of heavy rare earth elements required, thereby preserving magnetic remanence and reducing costs.

The patent employs composite materials by creating a multi-phase structure where heavy rare earth elements form a distinct grain boundary phase separate from the main Nd2Fe14B matrix. This composite structure allows the heavy rare earth elements to function specifically at the grain boundaries for coercivity enhancement, while the bulk material maintains its high magnetic remanence properties.

The patent applies local quality by concentrating heavy rare earth elements specifically at the grain boundaries through diffusion processes, rather than uniformly distributing them throughout the alloy. This localized approach enhances coercivity at the grain boundaries where it is most needed, while minimizing the overall amount of heavy rare earth elements required, thereby preserving magnetic remanence and reducing costs.

The patent applies partial action by using a low melting point alloy powder as a diffusion source that partially releases heavy rare earth elements during the heat treatment process. This controlled partial diffusion allows sufficient coercivity enhancement without requiring excessive amounts of heavy rare earth elements, thus reducing material costs while achieving the desired magnetic properties.

The patent introduces a low melting point alloy powder as an intermediary diffusion source that contains the heavy rare earth elements. This intermediary material simplifies the process by providing a controlled, gradual release of heavy rare earth elements during heat treatment, avoiding the need for direct coating and complex multi-stage grinding processes while achieving effective grain boundary diffusion.

The patent utilizes parameter changes by controlling the melting and diffusion behavior of the low melting point alloy powder during heat treatment. By adjusting the heat treatment temperature and time parameters, the heavy rare earth elements are controlled to diffuse appropriately into the grain boundaries, achieving the desired coercivity improvement through controlled parameter manipulation rather than complex process steps.