| AVS 62nd International Symposium & Exhibition | |
| Atom Probe Tomography Focus Topic | Monday Sessions |
| Session AP+AS+MC+MI+NS-MoM |
| Session: | Atom Probe Tomography of Nanomaterials |
| Presenter: | Taisuke Sasaki, National Institute for Materials Science (NIMS), Japan |
| Authors: | T. Sasaki, National Institute for Materials Science (NIMS), Japan T. Ohkubo, National Institute for Materials Science (NIMS), Japan K. Hono, National Institute for Materials Science (NIMS), Japan |
| Correspondent: | Click to Email |
(Nd,Dy)–Fe–B based sintered magnets are currently used for traction motors and generators of (hybrid) electric vehicles because of their excellent combination of maximum energy product and coercivity. However, there is a strong demand to achieve high coercivity without using Dy due to its scarce natural resources and high cost. In Nd-Fe-B sintered magnets, thin Nd-rich grain boundary (GB) phase is a key microstructural feature affecting the coercivity. Although Nd-rich phases, e.g. Nd-rich oxides and metallic Nd, located at grain boundary triple junctions affect the formation of the Nd-enriched grain boundary phase during post-sinter annealing, their phase constitution, distribution and orientation relationships are still under debate.
This presentation will introduce examples of advanced characterization works to establish the global microstructural feature that controls the coercivity of Nd-Fe-B sintered magnets, e.g. the clarification of phase constitution and distribution of Nd-rich phases at the grain boundaries by correlative SEM and TEM characterization, and the identification of the structure and chemistry of thin Nd-rich grain boundary phases by high resolution HAADF-STEM and 3D atom probe. We found the coercivity decrease by carbon impurity can be explained by the decrease in the RE (RE: Rare earth) content in the thin Nd-rich grain boundary phase.