Strategy of magnetic hardening region regulation enables a record enhanced energy product and high coercivity in Nd‐Fe‐B magnets

Abstract By developing high comprehensive performance (( BH ) max + H cj ), Nd‐Fe‐B magnets can operate stably in high‐temperature applications, greatly expanding the application scenarios of them. Unfortunately, there is a constraint relationship between coercivity ( H cj ) and maximum magnetic energy product (( BH ) max ), and an increase in H cj always accompanies a decrease in ( BH ) max . Here, the excellent comprehensive magnetic performance of up to 86.54, namely ( BH ) max of 42.33 MGOe and H cj of 44.21 kOe, is unprecedented in the sintered Nd‐Fe‐B magnets. This magnet is obtained by designing a unique grain structure through micrometallurgical reactions to prepare a matrix with excellent comprehensive performance, and then by stepwise diffusion, the ( BH ) max and H cj of the magnet are simultaneously enhanced. The magnet prepared in this way has a “double‐shell core” structure and Tb segregation distribution inside the core. The working temperature of the magnet in this work reached 280 °C, providing a new approach for the development of high‐performance Nd‐Fe‐B magnets.