# 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

## File

- [REPM2025_O5-2_Dirba.pdf](https://mdr.nims.go.jp/filesets/accf633a-30a2-449f-841d-215b88b6dc55/download) ([Detail](https://mdr.nims.go.jp/filesets/accf633a-30a2-449f-841d-215b88b6dc55.md))
- [(abstract) O5-2_Figure1.jpeg](https://mdr.nims.go.jp/filesets/6dc73a2c-86e5-4f27-98b1-1b840a0be155/download) ([Detail](https://mdr.nims.go.jp/filesets/6dc73a2c-86e5-4f27-98b1-1b840a0be155.md))

## Id

46776339-ed5e-4dfc-8136-c32a644d5192

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2025-08-13T08:08:36.427002Z

## Updated at

2025-08-20T03:30:47.096008Z

## Published at

2025-08-20T03:19:23.883344Z

## Doi

https://doi.org/10.48505/nims.5644

## First published url



## Date published



## Recorded date published



## Resource type

conference_presentation

## Manuscript type

na

## Collection

- id: d28f086a-61aa-4bc7-bcae-5a1078cbc6c7
  identifier: https://mdr.nims.go.jp/pid/d28f086a-61aa-4bc7-bcae-5a1078cbc6c7
  title: The 28th International Workshop on Rare Earth and Future Permanent Magnets
    and Their Applications (REPM2025)

## Title

- title: Reduction of heavy rare earths in Nd-Fe-B-based magnets by diffusion source
    and application area optimization
  title_type: original
  lang: en

## Description

- description: Reduction in critical heavy rare earth (HRE) elements such as Dy and
    Tb in NdFeB-based magnets for coercivity enhancement at the high operating temperature
    in E-motors is important for sustainable green energy transition. In this work,
    we maximize HRE utilization by selective hardening of areas in the magnet such
    as corners or edges that are highly susceptible to demagnetization, as demonstrated
    by Finite Element magnetostatics simulation on an internal permanent magnet synchronous
    traction motor for electric vehicles (Fig. 1a). Commonly industrially used HRE
    source TbHx as well as complex multicomponent Tb-containing alloys such as Tb10Pr60(Cu,Al,Ga)30
    are investigated on commercial grade NdFeB-based sintered magnets. For Tb hydride
    not only is the HRE utilization less efficient, but also the diffusion is more
    sluggish resulting in shorter diffusion depth. Highly efficient Tb utilization
    using small HRE amount comparable to trace elements added to commercial sintered
    magnets (e.g. Al, Cu, Ga) and good hightemperature performance is reached. Diffusing
    0.4 wt.% Tb results in coercivity of 1014 kA/m at 120 °C with only minor reduction
    in remanence from around 1.45 T in the initial magnet to 1.43 T after GBDP. To
    shed light on the HRE diffusion and local magnetic hardening, spatial coercivity
    mapping was done to investigate the local coercivity enhancement. The results
    are graphically illustrated in Fig. 1b. Corners clearly show the highest coercivity
    reaching nearly 1600 kA/m corresponding to 587 kA/m enhancement compared to the
    initial magnet. As expected for a diffusion-governed process, coercivity decrease
    is proportional to the distance from the diffusion source (corners).
  description_type: abstract
  lang: en

## Creator

- name: Imants Dirba
  role: author
  organization: Functional Materials, Institute of Materials Science, Technical University
    of Darmstadt, 64287 Darmstadt, Germany
- name: Abdullatif Durgun
  role: author
  organization: Functional Materials, Institute of Materials Science, Technical University
    of Darmstadt, 64287 Darmstadt, Germany
- name: Dominik Ohmer
  role: author
  organization: Vacuumschmelze GmbH & Co. KG, 63412 Hanau, Germany
- name: Matthias Katter
  role: author
  organization: Vacuumschmelze GmbH & Co. KG, 63412 Hanau, Germany
- name: Andreas Thul
  role: author
  organization: Institute of Electrical Machines (IEM), RWTH Aachen University, 52062
    Aachen, Germany
- name: Hossein Sepehri Amin
  role: author
  organization: National Institute for Materials Science, Tsukuba 305-0047, Japan
- name: Oliver Gutfleisch
  role: author
  organization: Functional Materials, Institute of Materials Science, Technical University
    of Darmstadt, 64287 Darmstadt, Germany

## Contact agent



## Publisher

organization: National Institute for Materials Science (NIMS)

## Managing organization



## Keyword

- subject: REPM2025
  schema: not_defined
- subject: permanent magnet
  schema: not_defined
- subject: Nd2Fe14B
  schema: not_defined
- subject: heavy rare earth
  schema: not_defined
- subject: grain boundary diffusion
  schema: not_defined
- subject: terbium
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

## Other identifier(s)



## Data origin

- data_origin_type: other

## Embargo



## Journal



## Conference

name: REPM2025
start_date: 2025-07-27
end_date: 2025-07-31
identifier: https://www.nims.go.jp/mmu/repm2025/

## Related item



## Funding



## Instrument



## Instrument operator



## Instrument managing organization



## Measurement method



## Specimen



## Chemical composition



## Structure for specimen



## Structural feature for specimen



## Specific property for specimen



## Process for specimen treatment



## Computational method



## Energy level/transition state



## Software



## Custom property



## Fileset

- id: accf633a-30a2-449f-841d-215b88b6dc55
  filename: REPM2025_O5-2_Dirba.pdf
  content_type: application/pdf
  size: 4176701
  md5: 26c81ef5e5b9ce002ee3dcd552409660
- id: 6dc73a2c-86e5-4f27-98b1-1b840a0be155
  filename: "(abstract) O5-2_Figure1.jpeg"
  content_type: image/jpeg
  size: 34160
  md5: 4ce463335fa21a7c2270ec9792d67548

## Thumbnail

fileset_id: accf633a-30a2-449f-841d-215b88b6dc55
filename: REPM2025_O5-2_Dirba.pdf