Effect of optimal aging treatment on magnetic performance and mechanical properties of sintered Nd-Fe-B permanent magnets

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• 作者：Xia Ding 丁霞 ; Kai-hong Ding 丁开鶿/a> ; Sheng-li Cui 崔胜冿/a>…
• 关键词：Nd ; Fe ; B permanent magnets ; aging treatment ; mechanical property ; acoustic emission ; fracture analysis ; Nd ; rich phase
• 刊名：Journal of Central South University
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：23
• 期：3
• 页码：515-522
• 全文大小：1,374 KB
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• 作者单位：Xia Ding 丁霞 (1)
  Kai-hong Ding 丁开鸿 (2)
  Sheng-li Cui 崔胜利 (2)
  Yong-cong Sun 孙永聪 (2)
  Mu-sen Li 李木森 (1)
  
  1. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials of Ministry of Education, Shandong University, Ji′nan, 250061, China
  2. Yantai Shougang Magnetic Materials Inc., Yantai, 265500, China
  
• 刊物类别：Engineering
• 刊物主题：Engineering, general
  Metallic Materials
  Chinese Library of Science
  
• 出版者：Central South University, co-published with Springer
• ISSN：2227-5223

文摘

The magnetic performance and mechanical properties including hardness, brittleness, fracture toughness and strength characteristics of the as-sintered and the optimal aged Nd-Fe-B magnets were examined in this work. A new method of Vickers hardness indentation combined with acoustic emission was used to test the brittleness of the magnets.The results show that the magnetic properties of the magnets could be improved through aging treatment, especially the intrinsic coercive force. But it is accompanied by a decrease of strength and fracture toughness. Theoretical calculation confirms that acoustic emission energy accumulated count value could be used to characterize the material brittleness. The bending fracture morphologies of the as-sintered and the optimal aged NdFeB magnets were investigated with the emphasis on the relationship between mechanical properties and microstructure using a field emission scanning electron microscopy (FE-SEM). The research results indicate that the intergranular fracture is the primary fracture mechanism for both as-sintered and optimal aged NdFeB magnets. Aging treatment changes the morphology and distribution of the Nd-rich phases, reducing the sliding resistance between Nd₂Fe₁₄B main crystal grains and lowers the grain boundary strength, which is the main reason for the strength and fracture toughness decrease of the aged Nd-Fe-B magnets.