Coercivity Enhancement of Nd–Ce–Fe–B Sintered Magnets by the Grain Boundary Diffusion Process Using Nd–Al–Cu Alloy

The grain boundary diffusion process using Nd-Al-Cu alloy has been applied to improve the coercivity and the thermal stability of Nd-Ce-Fe-B sintered magnets. The coercivity of Nd-Ce-Fe-B sintered magnets was substantially enhanced from 0.86 to 1.27 T. Microstructure observation indicated that the improved coercivity and the thermal stability resulted from the formation of Nd-rich core/shell microstructure and the distribution of intergranular phases, and microstructure parameters analyses confirmed the improved coercivity due to the enhanced magnetocrystalline anisotropy. This paper provides an economical way to prepare low-cost Ce-based sintered magnets with improved thermal stability.