Regulating fracture behaviors and mechanical properties of sintered Nd–Fe–B magnet by reconstructing grain boundaries

IF 9.6 1区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Rare Metals Pub Date : 2025-04-09 DOI:10.1007/s12598-025-03259-1

Xiao-Qian Bao, Ying Yu, Zi-Hao Wang, Shuo Gao, Hai-Jun Yu, Sheng-En Guan, Ji-Heng Li, Ming-Li Qin, Xue-Xu Gao

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Abstract

In this paper, the fracture behaviors and interface stresses of sintered Nd–Fe–B magnets were investigated. It was revealed that cracks propagated along the interfaces of Nd₂Fe₁₄B/Nd₂Fe₁₄B, Nd₂Fe₁₄B/Nd-rich phases and within Nd-rich phases. The misfits between 2:14:1 and Nd-rich phases were quantitatively determined, reflecting the concentration of interface stresses in magnet. Grain boundaries of magnet were reconstructed by diffusing Tb-containing and Tb-free sources, respectively. The Tb-rich shells at extensive layers of 2:14:1 grains caused lattice distortion, i.e., internal stresses, resulting in the crack mode changing from intergranular to transgranular in near surfaces of Tb-containing diffused magnets. Therefore, the bending strengths were deteriorated although the coercivities were apparently enhanced. In the case of Tb-free Pr–Cu diffused magnet, the Pr and Cu elements were enriched at grain boundaries, and the misfits between 2:14:1 and Nd-rich phases were declined, lowering interface stresses and strengthening grain boundaries. The mechanical and magnetic properties of Pr–Cu diffused magnet were simultaneously improved.

Graphical abstract

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重构晶界调控烧结钕铁硼磁体断裂行为和力学性能

研究了烧结钕铁硼磁体的断裂行为和界面应力。结果表明，裂纹沿Nd2Fe14B/Nd2Fe14B、Nd2Fe14B/富nd相界面及富nd相内部扩展。定量测定了2:14:1与富nd相之间的不匹配，反映了磁体中界面应力的集中。分别用含铽源和不含铽源对磁体的晶界进行了重建。在2∶14∶1晶粒宽层的富tb壳层引起晶格畸变，即内应力，导致含tb扩散磁体近表面裂纹模式由晶间裂纹转变为穿晶裂纹。因此，虽然矫顽力明显增强，但抗弯强度却有所下降。在无tb的Pr - Cu扩散磁体中，Pr和Cu元素在晶界处富集，2:14:1与富nd相的不匹配减小，界面应力降低，晶界强化。该材料的力学性能和磁性能同时得到改善。图形抽象

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来源期刊

Rare Metals 工程技术-材料科学：综合

CiteScore

12.10

自引率

12.50%

发文量

2919

审稿时长

2.7 months

期刊介绍： Rare Metals is a monthly peer-reviewed journal published by the Nonferrous Metals Society of China. It serves as a platform for engineers and scientists to communicate and disseminate original research articles in the field of rare metals. The journal focuses on a wide range of topics including metallurgy, processing, and determination of rare metals. Additionally, it showcases the application of rare metals in advanced materials such as superconductors, semiconductors, composites, and ceramics.