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
Materials Science, Multidisciplinary
Wenyue Song, Jiayi He, Hanjie Pan, Zhigao Yu, Jiali Cao, Wenbing Fan, Hongya Yu, Zhongwu Liu
Summary: Under certain conditions, the diffusion efficiency of heavy rare earth elements along the a-axis can be comparable to that along the c-axis. Alloying can enhance the diffusion along the a-axis, resulting in increased coercivity and reduced total consumption.
Article
Chemistry, Physical
Enxiang Yang, Weiyang Jin, Chao Man, Xiaolian Liu, Song Fu, Lan Bo, Shuainan Xu, Luyao Zhao, Zhi Li, Zhen Shi, Menglin Yu, Lizhong Zhao, Xuefeng Zhang
Summary: Grain boundary diffusion process has been applied for enhancing coercivity of Nd-Fe-B magnets by forming core-shell structure with less Tb consumption. However, excessively thick and asymmetric Tb-rich shells near the shallow diffused surface have minor contribution to coercivity enhancement and consume more Tb resources.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Feifei Li, Jiajie Li, Sajjad Ur Rehman, Lili Zhang, Yikuan Hu, Munan Yang, Xiaoqiang Yu, Shuwei Zhong, Tongxiang Liang
Summary: By utilizing composite powders for grain boundary diffusion, a significant improvement in coercivity of magnets can be achieved, while optimizing the microstructure can enhance the temperature coefficient of coercivity. Improved Pr-Al-rich grain boundary phases contribute to excellent diffusion efficiency and Dy diffusion depth.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Q. Feng, Y. L. Huang, H. F. Li, J. Y. Yu, C. Y. Wang, Z. J. Wu, Y. F. Yao, Y. H. Hou, W. Li, L. Ma, H. B. Yu
Summary: In this study, a DyCr film was prepared on the surface of Nd-Fe-B magnets through magnetron sputtering, and then subjected to grain boundary diffusion (GBD) to improve magnetic properties and enhance corrosion resistance. The results showed that the residual Cr-rich film acted as a protective coating to enhance corrosion resistance, and Cr element in the grain boundary phase improved the electrochemical potential. The coercivity was significantly improved, attributed to the formed Dy-rich shell and enhanced distribution of grain boundary phase.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Sangen Luo, Munan Yang, Zaiping Xu, Tongyun Zhao, Sajjad Ur Rehman, Xi Yu, Shuwei Zhong, Haitao Wang, Chaoxiang Jin, Qiang Ma, Bin Yang
Summary: This paper investigates the effect of grain size in the diffusion matrix on the grain boundary diffusion mechanism of Tb element. The results show that with only 0.75 wt. % TbF3 diffusion, the intrinsic coercivity increases significantly for the magnet with finer average grain size compared to the coarse-grain magnet. The increase in intrinsic coercivity is attributed to the increase in defect density and the higher grain orientation caused by grain refinement, which leads to improved diffusion efficiency and magnetic properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Erhao Wang, Caihai Xiao, Jiayi He, Cifu Lu, Mozaffar Hussain, Renheng Tang, Qing Zhou, Zhongwu Liu
Summary: The use of a grain boundary diffusion process with ZnO as the diffusion source has significantly enhanced the coercivity and corrosion resistance of sintered Nd-Fe-B magnets. The coercivity of the magnets increased significantly while the formation of oxides at triple junctions improved the corrosion resistance of the diffused magnets.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Wang Chen, Jiaying Jin, Shaoqing Ren, Baixing Peng, Liang Zhou, Chen Wu, Guozheng Liu, Mi Yan
Summary: Grain boundary diffusion process (GBDP) is usually used to modulate the surface microstructure of Nd-Fe-B magnets, but applying (Nd, Pr)Hx GBDP to Ce-substituted Nd-Ce-Fe-B magnets results in low coercivity due to the formation of REFe2 phase.
MATERIALS CHARACTERIZATION
(2022)
Article
Chemistry, Physical
Weitao Zhang, Yang Luo, Xiaojun Sun, Ze Zhang, Haijun Peng, Yuanfei Yang, Wenlong Yan, Zilong Wang, Dunbo Yu
Summary: In order to prepare high-quality nano-TbF3 coatings on Nd-Fe-B magnets more efficiently, Mg2+ and Cu2+ charging agents are added to the electrophoretic suspension. The addition of Mg2+ and Cu2+ can significantly improve the electrophoretic deposition efficiency and coating adhesion. The improvement in efficiency is attributed to the change in zeta potential of charged particles.
Article
Materials Science, Multidisciplinary
M. B. Siva Kumar, D. Prabhu, M. Sadhasivam, B. Manjusha, N. Chandrasekaran, K. G. Pradeep, G. Sundararajan, R. Gopalan
Summary: We investigated the effect of grain boundary diffusion of Nd-Cu eutectic phase and the influence of Nb on the microstructure and magnetic properties of Nd-Fe-B melt-spun ribbons. Our findings show that Nb clusters promote the decoration of Nd-Cu grain boundaries while limiting grain growth during diffusion annealing. The coercivity of the samples was significantly enhanced after diffusion annealing, making them suitable for high-temperature applications.
MATERIALS RESEARCH LETTERS
(2022)
Article
Crystallography
Xin-De Zhu, Mei Wang, Yong-Jiang Yu, Qian Wang, Fei Wang, Peng-Fei Wang, Bin Jia, Cong Wang, Bin Zhou
Summary: In this study, high-performance sintered Nd-Pr-Fe-B magnets were prepared using magnetron sputtering to deposit Dy/Tb films on the surface, which resulted in superior grain boundary diffusion (GBD) under heat treatments. The diffusion process was assessed using electron probe microanalyzer (EPMA) and inductively coupled plasma (ICP). The results showed enhanced coercivity and thermal stability in the Dy- and Tb-diffused magnets, with lower consumption of Dy/Tb compared to previous magnets with comparable coercivity. This work provides useful guidance for preparing low-cost and high-performance Nd-Fe-B magnets.
Article
Chemistry, Applied
Jinhao Zhu, Guangfei Ding, Lei Jin, Zhehuan Jin, Bo Zheng, Shuai Guo, Renjie Chen, Aru Yan
Summary: This study proposes a grain boundary modification approach using Nd-Ga addition to significantly enhance the coercivity of B-lean Nd-Fe-B sintered magnets. The coercivity is increased from 1.51 to 2.04 T by optimizing the microstructure and adjusting the phase composition of the grain boundary phase. The addition of Nd-Ga forms a continuous thin grain boundary phase and intermetallic Nd6Fe13Ga phases, resulting in improved magnetic properties.
JOURNAL OF RARE EARTHS
(2022)
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)
Article
Physics, Multidisciplinary
Zhiteng Li, Haibo Xu, Feng Liu, Rongshun Lai, Renjie Wu, Zhibin Li, Yangyang Zhang, Qiang Ma
Summary: This study investigates the influences of doping elements Ga and Zr on grain boundary diffusion (GBD) in Nd-Fe-B magnets. The results show that the Zr-doped magnet has the best GBD effect, leading to the highest coercivity increment. Ga can also improve diffusion depth, but its effect is not as significant as Zr. Microstructure analysis reveals that ZrB2 formed in the Zr-doped magnet plays a key role in increasing diffusion depth.
Article
Materials Science, Multidisciplinary
Jiakai Hu, Chuanxiao Peng, Hao Zhan, Xinyuan Bai, Li Wang
Summary: The effect of TbF3-Al diffusion source on the magnetic properties and microstructure of magnets was investigated. It was found that the Hcj of the TbF3-Al diffusion magnet increased by 40.9% compared to the original magnet, and the temperature stability was also improved. Microstructural investigations showed that aluminum can promote the formation of a Tb-rich thin grain boundary phase and increase the isolation between the main phases. Additionally, aluminum can promote the diffusion of TbF3 into the magnet.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
