Study on the high temperature magnetization reversal mechanism of grain boundary diffusion Nd–Fe–B sintered magnet by magnetic domain evolution observation

Abstract

Nd–Fe–B sintered magnets with ultrahigh coericivity of 47.1 kOe and maximum energy product of 38.5 MGOe have been successfully prepared by TbH3 nanoparticles grain boundary diffusion (GBD) process. Microstructural observations show that Tb enriches in the outer regions of 2:14:1 matrix phase grains, forming a core–shell structure. High temperature magnetic domain evolution observations indicate that reversed domains tend to nucleate at the outer regions of 2:14:1 matrix phase grains at 200 °C, while the Tb-rich shells show high magnetocrystalline anisotropy improving the nucleation field at outer regions, leading to enhancement of high temperature magnetic performance.