# Fileset

[REPM2025_O5-2_Dirba.pdf](https://mdr.nims.go.jp/filesets/accf633a-30a2-449f-841d-215b88b6dc55/download)

## Creator

Imants Dirba, Abdullatif Durgun, Dominik Ohmer, Matthias Katter, Andreas Thul, Hossein Sepehri Amin, Oliver Gutfleisch

## Rights

[Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/)

## Other metadata

[Reduction of heavy rare earths in Nd-Fe-B-based magnets by diffusion source and application area optimization](https://mdr.nims.go.jp/datasets/46776339-ed5e-4dfc-8136-c32a644d5192)

## Fulltext

Magnete – Schlüsselmaterialien auf dem Weg zur KlimaneutralitätReduction of heavy rare earths in Nd-Fe-B-based magnets by diffusion source and application area optimizationREPM2025, Tsukuba – 29 July 2025Imants Dirba1, Abdullatif Durgun1, Dominik Ohmer2, Matthias Katter2, Andreas Thul3, Hossein Sepehri Amin4, Oliver Gutfleisch11Functional Materials, Institute of Materials Science, Technical University of Darmstadt, 64287 Darmstadt, Germany,2Vacuumschmelze GmbH & Co. KG, 63412 Hanau, Germany, 3. Institute of Electrical Machines (IEM), 3RWTH Aachen University, 52062 Aachen, Germany, 4. National Institute for Materials Science, Tsukuba 305-0047, Japanimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 2What is the best GBDP HRE source?• Rare earth balance: 1 kg of Nd oxide produces 0.02 kg of Tb oxide• The highest ΔHc per HRE amount in the GBDP alloy: complex low-melting alloysTb10Pr60(CuAlGa)30Experimental:• Produced by melt spinning, applied on commercial N50 grade sintered magnets followed by a two-step heat treatmentGauß, R., Homm, G. and Gutfleisch, O. (2017),. J. Ind. Ecol. 21: 1291-1300.mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 3Grain boundary diffusion process optimization Coercivity enhancement saturates and HRE utilization decreases for high Tb amounts*Commercial grade VD722HR NdFeB-based sintered magnets from Vacuumschmelze GmbH mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 4The influence of the initial magnet (N50 grade)Jr =1.4 T, Hc=1990 kA/m (2.5 T) Hc= 747 kA/m (0.94) @ 150 °C Type 1Type 2Type 3Type 4mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 5Strategic local magnetic hardening2D FE-Simulated flux density distribution for a permanent magnet traction motor from electric vehicles The highest demagnetization at corners/edges. Local magnetic hardening via selected area GBDP?mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 6Strategic local magnetic hardeningc-axis“3D GBD”, “Gen 3”.. mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 7Local magnetic hardening – how to characterize?1234563D viewLocal coercivity mapping by measuring M(H) each for each individual segment mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 8Local coercivity mapping1234563D viewLocal coercivity mapping by measuring M(H) each for each individual segment ΔHc (kA/m)600400500c-planemailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 9Strayfield mapping using a 3D hall scannerLocal mapping of Bx, By, Bz above magnet surface across the hysteresis loopmailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 10Strayfield mapping using a 3D hall scannerLocal mapping of Bz above magnet surface across the hysteresis loopmailto:imants.dirba@tu-darmstadt.dereference corner centerimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 12MOIF - Magneto-Optical Indicator Films MOIFs as a tool for direct studies of the spatial distribution of magnetic fields and demagnetization processes in permanent magnets. High spatial resolution, large image range.Rotation of magnetization in MOIF under the effect of the sample’s stray fieldMagneto-optical contrast arises due to the Faraday effect MOIFMagnetMicroscopemailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 15Corrosion: Tb-Pr-Al-Cu-Ga vs TbHxTbHxTb10Pr60(AlCuGa)30After 1 year• Improved corrosion resistance for the Tb10Pr60(AlCuGa)30 GBDP compared to reference magnet and TbHx GBDP• Confirmed also after 1 year air exposure mailto:imants.dirba@tu-darmstadt.deimants.dirba@tu-darmstadt.de | REPM2025 Tsukuba 16Summary• Low melting Tb-Pr-Al-Cu-Ga alloys are promising for GBDP• HRE utilization drops significantly with increased GBDP amount• 0.3 wt.% Tb: Jr =1.4 T, Hc=1990 kA/m (2.5 T) & Hc= 747 kA/m (0.94 T) @ 150 °C • Efficient Tb utilization via selected area GBDP• Simple characterization using MOIF and 3D Hall scanner demonstrated• Improved corrosion resistance compared to TbHx and base magnetmailto:imants.dirba@tu-darmstadt.de