|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials Science for High-Performance Permanent Magnets
||Grain Boundary Diffusion of Different Rare Earth Elements in Nd-Fe-B Sintered Magnets by Experiment and FEM Simulation
||Konrad Löwe, Dimitri Benke, Tim Lienig, Michael Duerrschnabel, Leopoldo Molina-Luna, Konstantin P Skokov, Oliver Gutfleisch
|On-Site Speaker (Planned)
In the present work we explore the influence of a coercivity gradient in Nd-Fe-B magnets produced by the Grain Boundary Diffusion Process (GBDP) on the overall coercivity. We diffused four different rare earth elements (Dy, Tb, Ce and Gd) in commercial Nd-Fe-B magnets. By means of cutting the magnets into thin slices we obtain lateral coercivity profiles, from which diffusion constants are extracted. We find that in sintered magnets Tb diffuses significantly faster than Dy. Contrary to the magnets diffused with the heavy rare earths, the microstructure in the magnets treated with Ce show no (Nd,Ce)-Fe-B shells in the surface regions. Finally, a simple model for the magnetization reversal in grain boundary diffusion processed gradient Nd-Fe-B magnets was developed and implemented into an FEM software. The simulation indicates that the macroscopic coercivity of a gradient magnet depends mostly on the coercivity of its surface region.