RIP to extend compaction role

Rare earth permanent magnets are estimated to account for more than 10% of the sales value of the total world permanent magnet production. These magnets are used in a wide range of applications; particularly in those weight- and volume-conscious applications where use is made of their high energy products to achieve miniaturization of the permanent magnet device.The aim of this paper is to review the development of rare earth permanent magnets. The metallurgy and origin of the magnetic hardness of RCo5 and R2Co17 (R ≡ rare earth) SmCo-based permanent magnets are described. The recent developments of permanent magnets based on Nd2Fe14B are outlined. The processing of SmCo- and NdFeB-based permanent magnets is described and differences between their behaviour during processing are highlighted. Finally, the improvement and future development of NdFeB and related permanent magnets are discussed.