Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 50: Soft and hard permanent magnets

MA 50.7: Vortrag

Donnerstag, 15. März 2018, 16:30–16:45, EB 301

Anisotropic Effects of the Grain Boundary Diffusion Process (GBDP) in Textured Nd Fe B Magnets — •Tim Helbig, Andreas Abel, Simon Sawatzki, and Oliver Gutfleisch — TU Darmstadt

The Grain Boundary Diffusion Process (GBDP) is an industrially applied process to increase the coercivity of Nd-Fe-B sintered magnets using a minimal amount of heavy rare earth elements (HRE). In this process, the fully sintered and textured magnets are coated with a HRE or HRE compound and exposed to a heat treatment, causing the HRE to diffuse into the magnet. In order to investigate the texture dependence of this diffusion, a single face of a brick shaped sample was covered with Dy or Dy alloy and heat treated. Subsequently a coercivity profile was determined, by cutting the sample into small slices and measuring their coercivity individually. Simultaneously a second coercivity profile was derived by measuring the coercivity of the remaining sample piece after cutting each respective slice. The two data sets were compared allowing not only conclusions regarding the anisotropic grain boundary diffusion of Dy or Dy alloy, but also showed a pole surface hardening effect. This means that the compact magnet showed a higher coercivity than the average of its parts. Energy Dispersive X-ray spectroscopy (EDX) was used to relate the anisotropic diffusion of Dy to the obtained coercivity profile.

Financial support by the German federal state of Hessen through its LOEWE program "RESPONSE" is gratefully acknowledged.