Fine-grained NdFeB magnets prepared by low temperature pre-sintering and subsequent hot pressing

Fine-grained Nd10.79Pr2.8Al0.4B7.72Fe78.29 magnets were prepared by low temperature pre-sintering and subsequent hot pressing. The grain size of the magnets is just about 1–3 μm because the low sintering temperature results in no grain growth. The orientation degree, microstructure, and magnetic pro...

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Published inChinese physics B Vol. 24; no. 1; pp. 493 - 497
Main Author 剧锦云 唐旭 陈仁杰 汪金芝 尹文宗 李东 闫阿儒
Format Journal Article
LanguageEnglish
Published 2015
Subjects
Annealing
Grain boundaries
Grain size
Grains
Hot pressing
Magnetic properties
Magnets
Orientation
交换相互作用
低温
制备
晶粒尺寸
热压
细粒度
钕铁硼磁体
预烧结
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ISSN1674-1056
2058-3834
1741-4199
DOI10.1088/1674-1056/24/1/017504

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Summary:Fine-grained Nd10.79Pr2.8Al0.4B7.72Fe78.29 magnets were prepared by low temperature pre-sintering and subsequent hot pressing. The grain size of the magnets is just about 1–3 μm because the low sintering temperature results in no grain growth. The orientation degree, microstructure, and magnetic properties were studied. Some grains＇ easy axes deviate from the orientation direction, possibly due to grain rotation during the hot pressing. By subsequent annealing, the magnetic properties were significantly enhanced. Especially, the squareness of the demagnetization curve was improved greatly.The enhancement of coercivity by annealing can be explained by an improvement of both grain boundaries and magnetic isolation, which decouples the exchange interaction between neighboring grains.
Bibliography:Nd Fe B magnets; grain refinement; hot press; pre-sintering
Ju Jin-Yun,Tang Xu,Chen Ren-Jie,Wang Jin-Zhi,Yin Wen-Zong,Lee Don,Yan A-Ru（ 1.Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China ;2.Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China ;3.Ningbo University of Technology, Ningbo 315201, China）
11-5639/O4
Fine-grained Nd10.79Pr2.8Al0.4B7.72Fe78.29 magnets were prepared by low temperature pre-sintering and subsequent hot pressing. The grain size of the magnets is just about 1–3 μm because the low sintering temperature results in no grain growth. The orientation degree, microstructure, and magnetic properties were studied. Some grains＇ easy axes deviate from the orientation direction, possibly due to grain rotation during the hot pressing. By subsequent annealing, the magnetic properties were significantly enhanced. Especially, the squareness of the demagnetization curve was improved greatly.The enhancement of coercivity by annealing can be explained by an improvement of both grain boundaries and magnetic isolation, which decouples the exchange interaction between neighboring grains.
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ISSN:1674-1056
2058-3834
1741-4199
DOI:10.1088/1674-1056/24/1/017504