Core–shell Y-substituted Nd–Ce–Fe–B sintered magnets with enhanced coercivity and good thermal stability

Although Nd–Ce–Fe–B permanent magnets are inexpensive, they have degraded coercivity and poor thermal stability. To mitigate these disadvantages, in this work, we fabricated a core–shell grain structure with a Y-rich core and a (Nd, Ce)-rich shell in the Nd15.25(Ce1−xYx)15.25FebalAl0.1Cu0.1B (x = 0, 0.05, 0.10, 0.15, and 0.20) system by substituting Y for Ce. Substituting Y increased the coercivity from 7.13 kOe in the Ce1.00Y0.00 (x = 0) magnet to 9.73 kOe in the Ce0.85Y0.15 (x = 0.15) magnet. The thermal stability of its magnetic performance also improved with Y substitution, with lower temperature coefficients of remanence |α| and coercivity |β|. We explained these improvements in magnetic properties by examining the relationship between the microstructure and the properties of the core–shell grain structure.