Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets
Nd-Fe-B magnets containing no heavy rare earth (HRE) elements exhibit insufficient coercivity to withstand the demagnetization field at elevated temperatures. The grain boundary diffusion (GBD) process provides the best route to fabricate high-coercive Nd-Fe-B magnets with low consumption of expensi...
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| Format: | Article |
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MDPI AG
2021-09-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/11/9/1434 |
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| author | Jiayi He Jiali Cao Zhigao Yu Wenyue Song Hongya Yu Mozaffar Hussain Zhongwu Liu |
| author_facet | Jiayi He Jiali Cao Zhigao Yu Wenyue Song Hongya Yu Mozaffar Hussain Zhongwu Liu |
| author_sort | Jiayi He |
| collection | DOAJ |
| description | Nd-Fe-B magnets containing no heavy rare earth (HRE) elements exhibit insufficient coercivity to withstand the demagnetization field at elevated temperatures. The grain boundary diffusion (GBD) process provides the best route to fabricate high-coercive Nd-Fe-B magnets with low consumption of expensive HRE resources. Here we give a special review on the grain boundary diffusion sources and their coating methods. Up to now, various types of grain boundary sources have been developed, starting from the earliest Tb or Dy metal. The HRE-M eutectic alloys were firstly proposed for reducing the cost of the diffusion source. After that, the diffusion sources based on light rare earth and even non rare earth elements have also been proposed, leading to new understanding of GBD. Now, the diffusion sources including inorganic compounds, metals, and alloys have been employed in the industry. At the same time, to coat the diffusion source on the magnets before diffusion treatment, various methods have been developed. Different from the previous review articles for GBD, this review gives an introduction of typical types of diffusion sources and their fabrication approaches. The effects of diffusion source on the microstructure and magnetic properties are summarized briefly. In particular, the principles and applicability of different coating approaches were discussed in detail. It is believed that this review can provide a technical guidance for the industry for designing the diffusion process and products meeting specific requirements. |
| first_indexed | 2024-03-10T07:26:54Z |
| format | Article |
| id | doaj.art-4bf2ab776a444402af4f4989cb1ca930 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-10T07:26:54Z |
| publishDate | 2021-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-4bf2ab776a444402af4f4989cb1ca9302023-11-22T14:13:53ZengMDPI AGMetals2075-47012021-09-01119143410.3390/met11091434Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent MagnetsJiayi He0Jiali Cao1Zhigao Yu2Wenyue Song3Hongya Yu4Mozaffar Hussain5Zhongwu Liu6School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, ChinaSchool of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, ChinaSchool of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, ChinaSchool of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, ChinaSchool of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, ChinaDepartment of Physics, Air University, PAF Complex E-9, Islamabad 44000, PakistanSchool of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, ChinaNd-Fe-B magnets containing no heavy rare earth (HRE) elements exhibit insufficient coercivity to withstand the demagnetization field at elevated temperatures. The grain boundary diffusion (GBD) process provides the best route to fabricate high-coercive Nd-Fe-B magnets with low consumption of expensive HRE resources. Here we give a special review on the grain boundary diffusion sources and their coating methods. Up to now, various types of grain boundary sources have been developed, starting from the earliest Tb or Dy metal. The HRE-M eutectic alloys were firstly proposed for reducing the cost of the diffusion source. After that, the diffusion sources based on light rare earth and even non rare earth elements have also been proposed, leading to new understanding of GBD. Now, the diffusion sources including inorganic compounds, metals, and alloys have been employed in the industry. At the same time, to coat the diffusion source on the magnets before diffusion treatment, various methods have been developed. Different from the previous review articles for GBD, this review gives an introduction of typical types of diffusion sources and their fabrication approaches. The effects of diffusion source on the microstructure and magnetic properties are summarized briefly. In particular, the principles and applicability of different coating approaches were discussed in detail. It is believed that this review can provide a technical guidance for the industry for designing the diffusion process and products meeting specific requirements.https://www.mdpi.com/2075-4701/11/9/1434Nd-Fe-Bgrain boundary diffusioncoercivitydiffusion sourcecoating method |
| spellingShingle | Jiayi He Jiali Cao Zhigao Yu Wenyue Song Hongya Yu Mozaffar Hussain Zhongwu Liu Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets Metals Nd-Fe-B grain boundary diffusion coercivity diffusion source coating method |
| title | Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets |
| title_full | Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets |
| title_fullStr | Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets |
| title_full_unstemmed | Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets |
| title_short | Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets |
| title_sort | grain boundary diffusion sources and their coating methods for nd fe b permanent magnets |
| topic | Nd-Fe-B grain boundary diffusion coercivity diffusion source coating method |
| url | https://www.mdpi.com/2075-4701/11/9/1434 |
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