Core-shell microstructure of RE-Fe-B grains to achieve maximum coercivity: Industrial application

Abstract

Permanent magnets are vital components in the rapidly-developing renewable energy sector, where the motors for electric vehicles and the generators in wind turbines require strong magnets with the ability to operate at temperatures well over 100°C. To achieve high coercivity, remanence and consequently high energy product at elevated temperatures the addition of heavy rare earth (HRE) to the basic Nd-Fe-B composition is needed. To minimize the amount of critical elements such as dysprosium or terbium the grain boundary diffusion process is applied on sintered magnets. Instead of using dipping in slurry of HRE or expensive sputtering a new chemical process was invented - electrophoretic deposition (EPD).