Microstructural tailoring of the Crystal Size of the Recycled NdFeB Permanent Magnets for Enhanced Magnetic Performance in green Technologies

The recycling of NdFeB permanent magnets is currently attracting substantial research interest due to their potential for recycling and performance in green technologies, such as e-mobility and wind turbines. Consequently, the rare earth permanent magnets (RE-PMs) industry is very important to current energy and transportation systems, with a market value of around €6.5 billion in 2017. Similarly, the electric vehicle (EV) industry in the European Union (EU) is expected to be worth almost €500 billion by 2030, by creating about 6 million jobs. Therefore, a variety of End of Life (EoL) magnetic waste sources are being assessed as the potential feedstocks for the production of the PMs to fulfill performance standards in different applications. Subsequently, in this study, we modified and optimized the recycled NdFeB-PMs through a ball milling process, as well as investigating their microstructure, morphology, and magnetic properties. In addition, we modified the microstructure of the NdFeB PMs, achieving a crystal size ranging from 33 to 40 nm, with an excellent coercivity of 7.8-9.3 kA/m, and a good remanence of 85-103 emu/g after 10 hours of ball milling. Moreover, the implementation of the recycled magnets could make a substantial contribution to sustainability by reducing the dependency on countries with rich rare earth elements (REEs), consumption of raw materials, and lowering the overall CO₂ emissions caused by the production of PMs.