Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties
In this work, we successfully prepared heavy rare earth (HRE)-free Nd-Fe-B sintered magnets with improved coercivity (Hcj) and remanence (Br) by precisely controlling the grain size and optimizing the grain boundaries (GBs). Employing a low-temperature-sintering process, we achieved varying grain si...
Saved in:
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-03-01
|
| Series: | Journal of Materials Research and Technology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785425001747 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832586287647817728 |
|---|---|
| author | Yuxin Zhao Rui Han Meng Zheng Xun Duan Xiaoning Shi Xianjun Hu Hongsheng Chen Dong Zhou Shengzhi Dong Wei Li |
| author_facet | Yuxin Zhao Rui Han Meng Zheng Xun Duan Xiaoning Shi Xianjun Hu Hongsheng Chen Dong Zhou Shengzhi Dong Wei Li |
| author_sort | Yuxin Zhao |
| collection | DOAJ |
| description | In this work, we successfully prepared heavy rare earth (HRE)-free Nd-Fe-B sintered magnets with improved coercivity (Hcj) and remanence (Br) by precisely controlling the grain size and optimizing the grain boundaries (GBs). Employing a low-temperature-sintering process, we achieved varying grain sizes in the magnets. Specifically, the samples sintered at 920 °C had an average grain size of 2.35 μm, while the samples exhibiting the best magnetic properties had an average grain size of 2.51 μm. The fine-crystalline HRE-free magnets sintered at the optimal temperature demonstrated a superior coercivity of 16.29 kOe. Grain size refinement was found to be beneficial for enhancing the thermal stability of the magnets. Electron backscatter diffraction and X-ray diffraction analyses revealed that the fine-crystalline magnets displayed an improved crystallographic orientation, which correlates with the enhanced mobility of the magnetic powders. Transmission electron microscopy results indicated that the GBs in fine-crystalline magnets were thicker, with greater uniformity and continuity at triple junction points. We elaborate on the underlying mechanisms for the simultaneous enhancement of Br and Hcj in detail. Furthermore, first-order reversal curve (FORC) analysis confirmed that the fine-crystalline magnets exhibit superior temperature stability, attributed to a reduced local demagnetization field and a more independent demagnetization process. |
| format | Article |
| id | doaj-art-a9239a1532aa469ca8406e14082f0869 |
| institution | Kabale University |
| issn | 2238-7854 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Materials Research and Technology |
| spelling | doaj-art-a9239a1532aa469ca8406e14082f08692025-01-26T05:03:57ZengElsevierJournal of Materials Research and Technology2238-78542025-03-013519011912Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved propertiesYuxin Zhao0Rui Han1Meng Zheng2Xun Duan3Xiaoning Shi4Xianjun Hu5Hongsheng Chen6Dong Zhou7Shengzhi Dong8Wei Li9Division of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR China; Corresponding author.Division of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR China; School of Materials Science and Engineering, Anhui University, Hefei, Anhui, 230601, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaAdvanced Technology & Materials Co., Ltd, 76 Xueyuan South Road, Haidian District, Beijing, 100081, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaDivision of Functional Material, Central Iron & Steel Research Institute, Beijing, 100081, PR ChinaIn this work, we successfully prepared heavy rare earth (HRE)-free Nd-Fe-B sintered magnets with improved coercivity (Hcj) and remanence (Br) by precisely controlling the grain size and optimizing the grain boundaries (GBs). Employing a low-temperature-sintering process, we achieved varying grain sizes in the magnets. Specifically, the samples sintered at 920 °C had an average grain size of 2.35 μm, while the samples exhibiting the best magnetic properties had an average grain size of 2.51 μm. The fine-crystalline HRE-free magnets sintered at the optimal temperature demonstrated a superior coercivity of 16.29 kOe. Grain size refinement was found to be beneficial for enhancing the thermal stability of the magnets. Electron backscatter diffraction and X-ray diffraction analyses revealed that the fine-crystalline magnets displayed an improved crystallographic orientation, which correlates with the enhanced mobility of the magnetic powders. Transmission electron microscopy results indicated that the GBs in fine-crystalline magnets were thicker, with greater uniformity and continuity at triple junction points. We elaborate on the underlying mechanisms for the simultaneous enhancement of Br and Hcj in detail. Furthermore, first-order reversal curve (FORC) analysis confirmed that the fine-crystalline magnets exhibit superior temperature stability, attributed to a reduced local demagnetization field and a more independent demagnetization process.http://www.sciencedirect.com/science/article/pii/S2238785425001747HRE-free magnetsRefined grain sizeCoercivityThe orientation of magnets |
| spellingShingle | Yuxin Zhao Rui Han Meng Zheng Xun Duan Xiaoning Shi Xianjun Hu Hongsheng Chen Dong Zhou Shengzhi Dong Wei Li Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties Journal of Materials Research and Technology HRE-free magnets Refined grain size Coercivity The orientation of magnets |
| title | Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties |
| title_full | Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties |
| title_fullStr | Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties |
| title_full_unstemmed | Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties |
| title_short | Optimization of microstructure for HRE-free Nd-Fe-B magnets with improved properties |
| title_sort | optimization of microstructure for hre free nd fe b magnets with improved properties |
| topic | HRE-free magnets Refined grain size Coercivity The orientation of magnets |
| url | http://www.sciencedirect.com/science/article/pii/S2238785425001747 |
| work_keys_str_mv | AT yuxinzhao optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT ruihan optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT mengzheng optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT xunduan optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT xiaoningshi optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT xianjunhu optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT hongshengchen optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT dongzhou optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT shengzhidong optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties AT weili optimizationofmicrostructureforhrefreendfebmagnetswithimprovedproperties |