Magnetic domain switching in Nd–Fe–B sintered magnets with superior magnetic properties

Abstract

Nd–Fe–B sintered magnets with a giant intrinsic coercivity of 47.1 kOe and a high maximum energy product of 38.5 MGOe have been prepared via a combination of conventional sintering techniques and novel grain boundary diffusion process. Microstructural observations show that the Nd2Fe14B main phase grains in the magnets exhibit a core/shell type rare-earth elements distribution, where Tb enriched (Nd,Tb)2Fe14B phases are formed in the surface regions of the grains. Magnetic domain observations indicate that these modified surface regions strongly restrain the nucleation process of reversed magnetic domains, leading to a remarkable enhancement of the coercivity and overall magnetic performance of the magnets. Impact statement Nd–Fe–B sintered magnets with an unprecedented overall magnetic property have been fabricated with a novel approach, and the origin of magnetic property enhancement was elaborated via magnetic domain observation.

Keywords

• Nd–Fe–B sintered magnets
• coercivity enhancement
• grain boundary diffusion
• magnetic domain
• magnetic reversal process