Enhencement of magnetic properties of Tb-Al-Cu diffusion magnets depending on grain boundary diffusion process conditions

Abstract

The sintered Nd-Fe-B magnets have been widely used in the fields of a wide range of applications, such as hard disc drives, magnetic sensor, wind power generators, efficient air-conditioner compressors and motors for electric vehicles. Nd-Fe-B sintered magnets have a large maximum magnetic energy product, but in high-temperature environments such as the motors of eco-friendly cars, the coercivity decreases and performance deteriorates. To achieve high coercivity and remanence at high temperatures, heavy rare-earth (HRE) based grain boundary diffusion process (GBDP) is widely used. In this study, the temperature and time conditions of the GBDP process were optimized using a low-melting point HRE diffusion material based on Nd-Fe-B sintered magnets with Al and Cu added. The magnetic properties and microstructure of Tb-Al-Cu diffusion magnets with various compositions are discussed.