# Phase-field simulation of liquid-phase sintering coupled with a CALPHAD database of Nd-Fe-B-Cu system

https://mdr.nims.go.jp/datasets/87dc32e6-5c4e-4657-bd14-7490975d27ac

## File

- [REPM2025_O14-4_Ishii.pdf](https://mdr.nims.go.jp/filesets/56bc8160-d946-45d5-8e02-7b88f4ac0c21/download) ([Detail](https://mdr.nims.go.jp/filesets/56bc8160-d946-45d5-8e02-7b88f4ac0c21.md))

## Id

87dc32e6-5c4e-4657-bd14-7490975d27ac

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2025-08-18T02:56:37.311486Z

## Updated at

2025-08-20T03:30:19.612038Z

## Published at

2025-08-20T03:19:25.157266Z

## Doi

https://doi.org/10.48505/nims.5651

## 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: Phase-field simulation of liquid-phase sintering coupled with a CALPHAD database
    of Nd-Fe-B-Cu system
  title_type: original
  lang: en

## Description

- description: The coercivity of Nd–Fe–B sintered magnets is strongly influenced by
    their microstructure. High coercivity requires a compact microstructure consisting
    of small Nd2Fe14B (T1) grains uniformly covered with a thin grain boundary phase.
    To achieve such a microstructure, Nd−Fe−B sintered magnets are typically produced
    through sintering followed by postsinter annealing. The sintering process is liquid-phase
    sintering (LPS) because Nd-rich phases in the material liquefy at the sintering
    temperature (1000–1100 °C). During LPS, densification, grain growth, and liquid
    phase expansion determine the sintered compact density, T1 grain size, and final
    liquid phase distribution. The liquid phases, upon cooling to lower temperatures,
    transform into Nd-rich phases, which serve as a source of Nd for the formation
    of the thin grain boundary phase during post-sinter annealing. Therefore, predicting
    the microstructural evolution during LPS is crucial for enhancing the coercivity
    of Nd–Fe–B sintered magnets. Numerical simulation using the phase-field (PF) method
    is a promising numerical approach for predicting microstructural evolution during
    sintering. In our previous study, we have developed a PF model for LPS in multiphase
    and multicomponent systems. The PF model can analyze the microstructural evolution,
    including densification of the sintered compact, grain growth, phase transformation,
    and solute diffusion, by coupling with a CALPHAD database. In this study, we developed
    a PF simulation framework to analyze the microstructural evolution during LPS
    of Nd–Fe–B sintered magnets by coupling the PF model with a CALPHAD database of
    the Nd–Fe–B–Cu quaternary system. The PF simulation framework provided a thermodynamically
    consistent evolution of the Fe–15Nd–6B–0.1Cu (at%) alloy. By performing PF simulations
    under several conditions, we investigated key factors to optimize the microstructure
    leading to enhanced coercivity. In addition, we also investigated the solidification
    behavior of the T1 phase after sintering by lowering the temperature from the
    sintering temperature to 600 °C. This work was supported by Materials Open Platform
    for Permanent Magnet at NIMS.
  description_type: abstract
  lang: en

## Creator

- name: Akimitsu Ishii
  role: author
  organization: National Institute for Materials Science, Japan
- name: Toshiyuki Koyama
  role: author
  organization: National Institute for Materials Science, Japan
- name: Taichi Abe
  role: author
  organization: National Institute for Materials Science, Japan
- name: Machiko Ode
  role: author
  organization: National Institute for Materials Science, Japan

## Contact agent



## Publisher

organization: National Institute for Materials Science (NIMS)

## Managing organization



## Keyword

- subject: REPM2025
  schema: not_defined
- subject: Liquid-phase sintering
  schema: not_defined
- subject: Nd-Fe-B magnets
  schema: not_defined
- subject: Phase-field simulation
  schema: not_defined
- subject: CALPHAD
  schema: not_defined
- subject: Microstructure
  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: 56bc8160-d946-45d5-8e02-7b88f4ac0c21
  filename: REPM2025_O14-4_Ishii.pdf
  content_type: application/pdf
  size: 2208159
  md5: f6f92746d7fb3da4a553eda33bb43538

## Thumbnail

fileset_id: 56bc8160-d946-45d5-8e02-7b88f4ac0c21
filename: REPM2025_O14-4_Ishii.pdf