Article
Chemistry, Physical
Qingfang Huang, Qingzheng Jiang, Yao Shi, Sajjad Ur Rehman, Xing Wei, Zhixiang Li, Dawei Shi, Deqin Xu, Zhenchen Zhong
Summary: Post-sinter annealing is crucial for improving the microstructures and magnetic properties of NdFeB-based sintered permanent magnetic materials. It can significantly increase the intrinsic coercive force of the magnets. However, post-sinter annealing may cause a slight decrease in remanence, mainly due to the deteriorated orientation degree and reduced volume fraction of the hard magnetic main phases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Physics, Multidisciplinary
Jin-Hao Zhu, Lei Jin, Zhe-Huan Jin, Guang-Fei Ding, Bo Zheng, Shuai Guo, Ren-Jie Chen, A-Ru Yan
Summary: The study investigates the effects of post-sinter annealing on the microstructure and magnetic properties of Nd-Fe-B magnets with different Nd-Ga intergranular additions. The results show that the coercivity and remanence of the magnets change differently after annealing depending on the Nd-Ga concentrations. This is attributed to the evolution of the grain boundary structure after the annealing process.
Article
Chemistry, Physical
Zhehuan Jin, Guangfei Ding, Xiaodong Fan, Shuai Cao, Sining Fan, Zhixiang Wang, Bo Zheng, Shuai Guo, Renjie Chen, Aru Yan, Xincai Liu
Summary: The grain boundary diffusion process of Pr-Al-Cu at various temperatures in sintered Nd-Fe-B magnets and its influence on the magnetic properties were investigated. The results showed that the diffusion process resulted in the formation of shell phases rich in Pr and Al at 700 degrees C, which significantly enhanced the coercivity of the magnets after annealing. The thickness of the shell phase decreased during the annealing process and facilitated the formation of intergranular phases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Yuhui Chen, Hongliang Tao, Haojun Zhou, Yimin Li, Yuhang Yin, Fenghua Luo
Summary: Fe-Co-Cu alloys were prepared by pressureless sintering at 875 degrees C, and the effects of pre-alloyed Cu-15Sn sintering aids on the microstructure and mechanical properties were investigated. The results showed that the addition of Cu-15Sn changed the sintering process from solid phase to instantaneous liquid phase, improving the diffusion rate, relative density, and grain growth of the alloys. Adding 7 wt% Cu-15Sn significantly improved the relative density, hardness, and bending strength of the Fe-10 wt% Co-15 wt% Cu alloy. The volume fraction of Cu-rich phase, relative density, and grain size had a significant influence on the alloy's hardness and bending strength.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Mengjie Pan, Xiaolian Liu, Weiyang Jin, Song Fu, Enxiang Yang, Xianguo Liu, Lizhong Zhao, Xuefeng Zhang, Mi Yan
Summary: In this study, the corrosion resistance of Nd-Fe-B recycled magnets was improved by adding 0.3 wt% copper powder with an average grain size of 1 μm. The Cu-modified magnets showed significantly reduced mass loss in accelerated corrosion tests, which can be attributed to the change in crystal structure of the grain boundary phase after Cu modification.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Physical
Song Fu, Xiaolian Liu, Jiaying Jin, Zhiheng Zhang, Yongsheng Liu, Mi Yan
Summary: The formation of Nd6Fe13Ga phase and its impact on the performance of Nd-Fe-Cu-Ga-B magnets have been preliminarily explained in the study, and corresponding annealing process parameters have been formulated, providing important references for achieving high coercivity.
Article
Materials Science, Multidisciplinary
Wei Tang, Gaoyuan Ouyang, Baozhi Cui, Jing Wang, Kevin W. Dennis, Matthew J. Kramer, Iver E. Anderson, Jun Cui
Summary: The study explores the impact of grain size on magnetic and mechanical properties of Dy-free Nd-Fe-B sintered magnets, revealing that reducing grain size can enhance magnetic properties and thermal stability. However, controlling Oxygen content is crucial in balancing magnetic and mechanical properties.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Physical
Mario Schoenfeldt, Urban Rohrmann, Philipp Schreyer, Mahmudul Hasan, Konrad Opelt, Juergen Gassmann, Anke Weidenkaff, Oliver Gutfleisch
Summary: The effects of multiple recycling of scrap magnets from magnetic resonance tomography devices were investigated. The changes in different material properties were studied, including chemical composition, impurity content, particle size, magnetic properties, microstructure, and degree of alignment. The recycling process led to a decrease in texture, orientation, and magnetic properties, as well as an increase in impurities and particle size. The addition of Nd hydride improved the properties, with 4 wt.% Nd hydride fully restoring the density of the recycled magnets. The recycled magnets met the specification of primary magnets and outperformed them in terms of sustainability and production cost reduction.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Liu Tao, Zhang Xin, Li Jian, Chen Jie, Cheng Xinghua, Zhou Lei, Yu Xiaojun, Li Bo
Summary: The Nd-Fe-B base magnets with different (Al+Cu) contents were treated with Dy grain boundary diffusion process, and it was found that the coercivity of the high (Al+Cu) magnets is significantly higher than that of the low (Al+Cu) magnets, despite the same Dy increment. The analysis also revealed that the Dy-rich shells are distributed more clearly and continuously in the high (Al+Cu) magnets, with higher Dy concentration near the grain boundary region, resulting in enhanced coercivity.
RARE METAL MATERIALS AND ENGINEERING
(2021)
Article
Nanoscience & Nanotechnology
Y. M. Tao, J. Y. Jin, L. Z. Zhao, X. L. Liu, Z. H. Zhang, G. H. Bai, C. Wu, J. M. Greneche, K. Lv, B. Xin, M. Yan
Summary: Grain boundary (GB) engineering is used to control the composition and magnetism of the 1:2 phase in Nd-Ce-Fe-B nanostructured magnets. A Cu-mediated GB engineering strategy is proposed, which enables the formation of a continuous 1:2 GB phase and the generation of a novel Nd-dominated 1:2 phase with a ferro-paramagnetic transformation. At the optimal Cu doping, the magnet exhibits the highest coercivity and coexistence of paramagnetic and ferromagnetic 1:2 phases.
MATERIALS TODAY NANO
(2022)
Article
Chemistry, Applied
Jinhao Zhu, Guangfei Ding, Bo Zheng, Haichen Wu, Lei Jin, Zhehuan Jin, Shuai Guo, Renjie Chen, Aru Yan
Summary: By adding Pr-Cu-Ti alloy powders, the grain boundary and local composition system of Nd-Fe-B magnets can be optimized, leading to an increase in coercivity. The addition of the alloy induces the generation of thin grain boundary phases, promoting intergrain exchange decoupling and increasing the coercivity. However, excess addition results in structural defects and further improvement in microstructure is needed.
JOURNAL OF RARE EARTHS
(2022)
Article
Materials Science, Multidisciplinary
Van Dao Nguyen, Taek-soo Kim, Babu Madavali, Sung Jae Jo, Jin Gyu Lee, Gian Song, Soon-jik Hong
Summary: In this study, the formation of columnar grain microstructure of melt-spun Nd-Fe-B alloy was investigated and its effect on the magnetic properties of the spark plasma sintered Nd-Fe-B bulk was studied. The formation of columnar grains perpendicular to the ribbon plane was examined through SEM, while XRD results showed a strong (00 l) crystal texture. The mechanisms behind the formation of columnar grains and the magnetic properties of the sintered Nd-Fe-B bulks were discussed. The obtained Nd-Fe-B magnet demonstrated enhanced magnetic properties by controlling the microstructure of the melt-spun ribbons, including columnar grain regions and equiaxed grain regions.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Xia Ding, Xiu-Chun Wang, Kai-Hong Ding, Sheng-Li Cui, Yong-Cong Sun, Mu-Sen Li
Summary: The corrosion-resistant coating formed by phosphate chemical conversion treatment on sintered Nd-Fe-B magnets significantly improves their corrosion resistance without compromising magnetic properties, providing an effective way to enhance the corrosion resistance of these magnets.
Article
Chemistry, Applied
Xiaolian Liu, Mengjie Pan, Pei Zhang, Tianyu Ma, Lizhong Zhao, Lingwei Li
Summary: Homogeneous substitution of Dy for Nd in the 2:14:1 phase can enhance coercivity but reduce remanence. A comparative study showed that multi-main-phase magnet with inhomogeneous Dy distribution has better magnetic properties and thermal stability than single-main-phase magnet with homogeneous Dy distribution. The multi-main-phase magnet exhibited higher coercivity, remanence, and energy product at room temperature and over a wide temperature range.
JOURNAL OF RARE EARTHS
(2021)
Article
Materials Science, Multidisciplinary
Shulin Diao, Yang Luo, Wenlong Yan, Haijun Peng, Yi Dong, Haibo Yi, Shujie Wu, Shuai Zhang, Dunbo Yu
Summary: The effects of different Al content on the microstructure and magnetic properties of Nd-Fe-B magnets after Tb diffusion were investigated. It was found that low Al content magnets showed increased thickness of Tb shell and coercivity, while high Al content magnets had decreased Tb diffusion and lower density of Tb shell.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
