BSTRACTNd–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 Nd

2

Fe

14

B main phase grains in the magnets exhibit a core/shell type rare-earth elements distribution

where Tb enriched (Nd

Tb)

2

Fe

14

B 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.