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学者姓名：岳明
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Abstract ：
The application of bulk nanocrystalline Nd-Fe-B permanent magnets manufactured by hot deformation methods was severely limited by production efficiency. Therefore, this work proposed an efficient preparation method combining hot rolling and deformation. Using the melt-spun Nd-Fe-B magnetic powders as original materials, dense, large-sized, and well-uniform precursors for deformation can be obtained through cold pressing and hot rolling. The large-sized hot-rolled magnet can be cut into small pieces and subjected to hot deformation. The deformed magnet exhibits obvious crystallographic anisotropy, and the optimal maximum energy product can reach 35.7 MGOe. Furthermore, the mechanism of deformation and texture formation has been systematically studied, according to the microstructure and texture characterization of different height reduction magnets. The results indicated that there was a typical heterogeneous structure in the hot-rolled and hot-deformed Nd-Fe-B magnets. Dissolution precipitation, grain growth, and regular grain arrangement were the main reasons for deformation and texture formation during the deformation process. Our strategy of replacing traditional hot-pressing with large-sized hot-rolling can produce massively deformed precursors at once, greatly improving production efficiency, which is crucial for promoting the application of bulk nanocrystalline anisotropic Nd-Fe-B permanent magnets. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.
Keyword ：
Deformation behavior Deformation behavior Hot deformation Hot deformation Magnetic properties Magnetic properties Anisotropic Nd-Fe-B magnet Anisotropic Nd-Fe-B magnet Hot rolling Hot rolling
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| GB/T 7714 | Li, Qian , Liu, Lingqi , Li, Yuqing et al. New strategy for efficient manufacturing of bulk anisotropic nanocrystalline Nd-Fe-B permanent magnets [J]. | JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY , 2024 , 201 : 119-129 . |
| MLA | Li, Qian et al. "New strategy for efficient manufacturing of bulk anisotropic nanocrystalline Nd-Fe-B permanent magnets" . | JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY 201 (2024) : 119-129 . |
| APA | Li, Qian , Liu, Lingqi , Li, Yuqing , Yue, Ming , Teng, Yuan , Liu, Weiqiang et al. New strategy for efficient manufacturing of bulk anisotropic nanocrystalline Nd-Fe-B permanent magnets . | JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY , 2024 , 201 , 119-129 . |
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Abstract ：
With the rapid development of application fields, such as the green energy industry, has resulted in increased demand for magnetic characteristics, especially the coercivity (Hcj). In this paper, two types of (Nd, Dy) -Fe -B magnets with comparable Hcj values were prepared using by grain boundary diffusion (GBD) method and dual alloy (DA) method. The composition, microstructure, domain structure, and magnetization reversal process of GBD and DA magnets were subjected to comparison. Additionally, an analysis of the specific coercivity mechanism was also conducted by fitting the Brown's equation. The results of composition and microstructure analysis revealed the formation of core-shell structural grains were formed in both GBD and DA methods. Specifically, the GBD method exhibited a higher concentration of Dy in the shell, constituting 26.8 % of the total rare earth (RE) content. In contrast the DA magnets had Dy accounting for 15.8 % of the total RE content in the shell. This discrepancy was identified as the primary factor contributing to the superior efficiency in enhancing the coercivity (Hcj) observed in the GBD method. The fitting results showed that GBD magnets were more inclined to nucleate in the core region in grain, whereas DA magnets nucleate at the edge of the grain shell layer. Both the observation of magnetic domains and magnetization reversal processes analysis revealed that the demagnetization process in GBD magnets is more uniform, which leads to better squareness. Our finding can provide theoretical and experimental basis for the preparation of high -performance Nd-Fe-B magnets.
Keyword ：
Rare earth permanent magnet materials Rare earth permanent magnet materials Grain boundary diffusion Grain boundary diffusion Coercivity Coercivity Nd-Fe-B Nd-Fe-B Dual alloy method Dual alloy method
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| GB/T 7714 | Qin, Yuan , Li, Yuqing , Wang, Zhanjia et al. Analysis on coercivity enhancement mechanism of grain-boundary-diffused and Dual-alloyed Nd-Fe-B Magnets [J]. | JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T , 2024 , 29 : 1805-1812 . |
| MLA | Qin, Yuan et al. "Analysis on coercivity enhancement mechanism of grain-boundary-diffused and Dual-alloyed Nd-Fe-B Magnets" . | JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T 29 (2024) : 1805-1812 . |
| APA | Qin, Yuan , Li, Yuqing , Wang, Zhanjia , Wu, Haihui , Zhang, Lele , Liu, Weiqiang et al. Analysis on coercivity enhancement mechanism of grain-boundary-diffused and Dual-alloyed Nd-Fe-B Magnets . | JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T , 2024 , 29 , 1805-1812 . |
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Abstract ：
The precipitation-hardened Sm-Co permanent magnets relied on the pinning of nanocellular structures to achieve high coercivity, and have an irreplaceable position in high-temperature applications. In this article, by employing micromagnetic simulations and magnetic domain observations, the pinning behavior of lamellar phases (Zphase) were investigated, which has not been well understood before. The results showed that the Z-phase can serve as a strong pinning position, but due to the parallel lamellar distribution, the magnetic domain walls can move around. Additionally, the effect of Z-phase on coercivity was achieved by changing the morphology of magnetic domain walls during magnetization reversal. For attractive pinning, the coercivity was reduced by the Z-phase, while for repulsive pinning, the Z-phase increased the coercivity when gamma Z<0.54 gamma H. Our findings can provide a novel understanding of the coercivity mechanism of precipitation-hardened Sm-Co permanent magnets.
Keyword ：
Magnetization reversal Magnetization reversal Pinning Pinning Magnetic domain Magnetic domain Permanent magnet Permanent magnet Micromagnetic simulation Micromagnetic simulation
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| GB/T 7714 | Li, Yuqing , Liu, Manying , Zhang, Dongtao et al. Lamellar Zr-rich phase and its influence on coercivity for Sm(CoFeCuZr) z magnets [J]. | JOURNAL OF ALLOYS AND COMPOUNDS , 2024 , 1009 . |
| MLA | Li, Yuqing et al. "Lamellar Zr-rich phase and its influence on coercivity for Sm(CoFeCuZr) z magnets" . | JOURNAL OF ALLOYS AND COMPOUNDS 1009 (2024) . |
| APA | Li, Yuqing , Liu, Manying , Zhang, Dongtao , Zhang, Lele , Wu, Qiong , Xia, Weixing et al. Lamellar Zr-rich phase and its influence on coercivity for Sm(CoFeCuZr) z magnets . | JOURNAL OF ALLOYS AND COMPOUNDS , 2024 , 1009 . |
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Abstract ：
The precipitation-hardening Sm-Co magnets not only have irreplaceable applications under extreme conditions such as high temperatures, but are also the most typical magnets with pinning-controlled magnetization reversal mechanism. However, there have always been two views on this type of pinning, attractive or repulsive. In this article, the modification of the parallel interface to the titled interface, led to occurrence of quasi-repulsive and quasi-attractive pinning modes, by employing micromagnetic simulation methods. The corresponding domain wall energy relationship between the pinning phase and main phase was analyzed for different pinning modes, according to the morphology of domain wall from the simulation results. The analysis results indicated that relatively small difference in domain wall energy between the two phases led to quasi-repetitive and quasi-attractive pinning modes. Our findings can provide a reference for further understanding of the magnetization reversal mechanism of precipitation-hardening Sm-Co magnets. The emphasis on the influence of 1:5/2:17 interface orientation on pinning also provided a perspective on the magnetization reversal mechanism of other nanostructured permanent magnet materials.
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| GB/T 7714 | Liu, Manying , Li, Yuqing , Zhang, Dongtao et al. Understanding of magnetization reversal mechanism of precipitation-hardening samarium-cobalt magnets from micromagnetic simulation [J]. | APPLIED PHYSICS LETTERS , 2024 , 124 (4) . |
| MLA | Liu, Manying et al. "Understanding of magnetization reversal mechanism of precipitation-hardening samarium-cobalt magnets from micromagnetic simulation" . | APPLIED PHYSICS LETTERS 124 . 4 (2024) . |
| APA | Liu, Manying , Li, Yuqing , Zhang, Dongtao , Wu, Qiong , Yang, Jianjun , Zhang, Hongguo et al. Understanding of magnetization reversal mechanism of precipitation-hardening samarium-cobalt magnets from micromagnetic simulation . | APPLIED PHYSICS LETTERS , 2024 , 124 (4) . |
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Abstract ：
The highly efficient and green recycling of sintered Nd-Fe-B sludge has emerged as a pressing concern in light of the escalating production of sludge. In this work, a novel ultra-short process strategy of purification-remixing incorporation is proposed for in-situ regeneration across several types of Nd-Fe-B sludges. The magnetic properties of the regenerated magnets are effectively restored by remixing the purified sludge at 30 wt% into customized high-remanence magnetic powder, followed by the adjustment of rare earth content to 30.5 % using rare earth-rich compounds. For magnets using 48SH sludge, the remanence and coercivity are recovered to 13.8 kG and 22.2 kOe, respectively, with recovery rates of 97 % and 108.3 %, which are almost as high as those of the original magnets. The temperature stability of the magnet is comparable to that of the original magnet as well. The comprehensive analysis attributes the attainment of high-performance to the repair and optimization of the microstructure, particularly focusing on the grain boundary phase.The ultra-short recovery process and the reuse of solvents in the purification phase minimize the total energy consumption and carbon emissions, and show great potential for green recycling for Nd-Fe-B sludge.
Keyword ：
Nd-Fe-B sludge Nd-Fe-B sludge In-situ regeneration In-situ regeneration Ultra-short process Ultra-short process Separation and purification Separation and purification
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| GB/T 7714 | Yu, Lichao , Lu, Qingmei , Yang, Xinyuan et al. New strategy for the ultra-short process regeneration of sintered Nd-Fe-B sludge via purification-remixing incorporation [J]. | SEPARATION AND PURIFICATION TECHNOLOGY , 2024 , 350 . |
| MLA | Yu, Lichao et al. "New strategy for the ultra-short process regeneration of sintered Nd-Fe-B sludge via purification-remixing incorporation" . | SEPARATION AND PURIFICATION TECHNOLOGY 350 (2024) . |
| APA | Yu, Lichao , Lu, Qingmei , Yang, Xinyuan , Liu, Weiqiang , Dong, Gaihua , Huang, Shulin et al. New strategy for the ultra-short process regeneration of sintered Nd-Fe-B sludge via purification-remixing incorporation . | SEPARATION AND PURIFICATION TECHNOLOGY , 2024 , 350 . |
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Abstract ：
The grinding sludge of grain boundary diffusion Nd-Fe-B magnet is rich in heavy rare earth and has a typical core-shell microstructure. In this work, an ultra-short process was developed to realize green, in-situ regeneration of the sludge and efficient reuse of heavy rare earth elements. The regenerated magnets showed excellent magnetic performance and good temperature stability which were fabricated after the purification of sludge, composition regulation with rare earth-rich compounds, Nd42.1FebalB0.79, NdHx, (PrNd)H-x, and sintering. Especially, the magnet prepared by using Nd42.1FebalB0.79 alloy had significant property recovery, where remanence and coercivity were restored to 12.8 kG, and 20.6 kOe, respectively, reaching 97.7 % and 162.5 % of the original magnet. The magnetization reversal behavior and the coercivity mechanism were analyzed to keep the nucleation mechanism, and the high coercivity stemmed from the repair and optimization of the grain boundary by introducing rare earth-rich alloys, the full utilization of heavy rare earth elements, and the core-shell microstructure rooted in the sludge as well.
Keyword ：
Nd-Fe-B sludge Nd-Fe-B sludge In-situ regeneration In-situ regeneration Ultra-short process Ultra-short process HRE HRE
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| GB/T 7714 | Yu, Lichao , Lu, Qingmei , Cong, Liying et al. Achieving high-performance regeneration of grain boundary diffusion Nd-Fe-B sludge via an ultra-short process [J]. | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS , 2024 , 610 . |
| MLA | Yu, Lichao et al. "Achieving high-performance regeneration of grain boundary diffusion Nd-Fe-B sludge via an ultra-short process" . | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 610 (2024) . |
| APA | Yu, Lichao , Lu, Qingmei , Cong, Liying , Yang, Xinyuan , Liu, Weiqiang , Dong, Gaihua et al. Achieving high-performance regeneration of grain boundary diffusion Nd-Fe-B sludge via an ultra-short process . | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS , 2024 , 610 . |
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Abstract ：
Hard magnetic materials based on SmCo5, known for their high coercivity, have found extensive applications in advanced technologies. To further enhance their magnetic performance, it is advantageous to reduce the particle size slightly below the single-domain limit and modify the shape to a one-dimensional (1D) structure. Here, two strategies were introduced with the aim to synthesize the anisotropic SmCo5 nanostructured magnetic powder. The first approach involving electrospinning and reduction-diffusion failed to generate the desired one-dimensional structure, resulting in zero-dimensional (0D) SmCo5 spherical particles with a coercivity of 34.5 kOe and a maximum magnetic energy product of 14 MGOe. In contrast, the second approach, which combines the modified polyol process with reduction-diffusion, yielded a SmCo5 magnetic powder with two distinct morphologies: zero-dimensional spherical particles and one-dimensional nanofibers. The SmCo5 magnetic powder synthesized by the second method exhibits a coercivity of 47.2 kOe and a maximum magnetic energy product of 17 MGOe, significantly exceeding those reported for zero-dimensional spherical SmCo5 nanoparticles. This high-performance SmCo5 magnetic powder holds considerable promise for high-density data storage and permanent magnet applications. Moreover, it provides avenues for developing exchange-coupled nanocomposite magnets with a high energy density. The findings of this study may serve as the foundation for exploiting anisotropic SmCo5 nanomagnets and hold significant implications for the design of advanced magnetic materials using the reduction-diffusion method.
Keyword ：
rare-earth permanent magnets rare-earth permanent magnets anisotropy anisotropy SmCo5 SmCo5 coercivity coercivity chemical synthesis chemical synthesis
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| GB/T 7714 | Yang, Zhi , Wang, Yatao , Xu, Haibo et al. Strategies for the Synthesis of Nanostructured SmCo5 Magnetic Particles for Permanent Magnetic Application [J]. | ACS APPLIED NANO MATERIALS , 2024 , 7 (4) : 4252-4263 . |
| MLA | Yang, Zhi et al. "Strategies for the Synthesis of Nanostructured SmCo5 Magnetic Particles for Permanent Magnetic Application" . | ACS APPLIED NANO MATERIALS 7 . 4 (2024) : 4252-4263 . |
| APA | Yang, Zhi , Wang, Yatao , Xu, Haibo , Wu, Qiong , Zhang, Hongguo , Liu, Weiqiang et al. Strategies for the Synthesis of Nanostructured SmCo5 Magnetic Particles for Permanent Magnetic Application . | ACS APPLIED NANO MATERIALS , 2024 , 7 (4) , 4252-4263 . |
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Abstract ：
The synthesis of size-controlled Sm2Fe17 magnetic particles is a prerequisite for the fabrication of highperformance Sm2Fe17N3 permanent magnetic materials. Here, Sm2Fe17 was synthesized using a costeffective reduction-diffusion method. The calcium chloride molten salt was introduced to control the particle size and achieve a single phase of Sm2Fe17. The effects of reduction-diffusion reaction temperature and the amount of added calcium chloride on the phase constitution and microstructure of the final product of reduction-diffusion were systematically investigated. Adding an appropriate amount of calcium chloride can effectively inhibit the overgrowth and sintering of the reduced particles. By employing the strategy of adding 20 wt% of calcium chlorides into the green compacts, we were able to successfully synthesize uniform Sm2Fe17 particles that are well-dispersed, with an average size of 2.2 mm. Furthermore, by combining the optimal reduction-diffusion conditions and the nitriding process, the hard magnetic Sm2Fe17N3 material was successfully obtained. This study could be useful for the development of high-performance Sm2Fe17N3 magnetic materials utilizing reduction-diffusion technology. (c) 2023 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Keyword ：
Molten salt Molten salt Permanent magnets Permanent magnets Rare earths Rare earths Reduction-diffusion Reduction-diffusion
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| GB/T 7714 | Xi, Junhua , Yang, Zhi , Haseeb, Muhammad et al. Synthesis of size-controlled and dispersible Sm2Fe17N3 magnetic particles by reduction diffusion process using molten salt* [J]. | JOURNAL OF RARE EARTHS , 2024 , 42 (11) : 2105-2111 . |
| MLA | Xi, Junhua et al. "Synthesis of size-controlled and dispersible Sm2Fe17N3 magnetic particles by reduction diffusion process using molten salt*" . | JOURNAL OF RARE EARTHS 42 . 11 (2024) : 2105-2111 . |
| APA | Xi, Junhua , Yang, Zhi , Haseeb, Muhammad , Chen, Yuanyuan , Nie, Xiaofeng , Cong, Liying et al. Synthesis of size-controlled and dispersible Sm2Fe17N3 magnetic particles by reduction diffusion process using molten salt* . | JOURNAL OF RARE EARTHS , 2024 , 42 (11) , 2105-2111 . |
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Abstract ：
As a new technology for the short-process recovery of Nd-Fe-B sintered magnet sludge, the calcium thermal reduction diffusion method has attracted significant attention due to its low energy consumption, environmental friendliness, and high recovery rate. However, traditional calcium thermal reduction diffusion technology still has issues such as an insufficient reaction between the sludge and reducing agent after increasing the amount of reactants, the use of a large amount of reducing agent, and low recovery efficiency. Therefore, a novel dynamic calcium thermal reduction diffusion technology was proposed, with the calcium reduction diffusion of sludge and calcium undergoing a continuous mixing and diffusion state throughout the entire process, greatly improving the efficiency of the reaction. Compared with the traditional process, the amount of reactants was increased from a few grams to hundreds of grams, and the amount of reducing agent calcium was reduced by 25%. Subsequently, regenerated magnetic powder with a uniform particle size, good dispersion, and excellent magnetic properties was obtained. The saturation magnetization under a 3 T magnetic field was increased by 27.9% compared with the initial sludge. The maximum magnetic energy product of the magnet prepared by doping 50 wt% regenerated magnetic powder was 45 MGOe, which reached the highest level of the regenerated magnets prepared by recycling sludge. What is encouraging that this new technology had the advantage of achieving large-scale production and reducing production costs, providing a potential industrialization solution for the green and efficient recovery of Nd-Fe-B sintered magnet sludge.
Keyword ：
Large-scale production Large-scale production Dynamic Dynamic Nd-Fe-B sintered magnet sludge Nd-Fe-B sintered magnet sludge Calcium thermal reduction diffusion Calcium thermal reduction diffusion Short -process recovery Short -process recovery
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| GB/T 7714 | Cong, Liying , Xu, Haibo , Lu, Qingmei et al. An efficient process for preparing regenerated magnets by dynamic recovery of Nd-Fe-B sintered magnet sludge [J]. | JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING , 2024 , 12 (2) . |
| MLA | Cong, Liying et al. "An efficient process for preparing regenerated magnets by dynamic recovery of Nd-Fe-B sintered magnet sludge" . | JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 12 . 2 (2024) . |
| APA | Cong, Liying , Xu, Haibo , Lu, Qingmei , Yu, Lichao , Zhou, Quangui , Wu, Qiong et al. An efficient process for preparing regenerated magnets by dynamic recovery of Nd-Fe-B sintered magnet sludge . | JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING , 2024 , 12 (2) . |
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Abstract ：
M-type ferrite exhibits good magnetic characteristics and resistance to oxidation, enabling the production of stable nanoparticles for applications such as medical delivery, hyperthermia therapy, and magnetic recording. Additionally, it serves as a valuable tool for studying the theory of coercivity. Here, the impact of surface and size on coercivity and associated mechanisms in M-type hexagonal ferrites has been thoroughly analyzed by a combination of micromagnetic models and experimental investigations. Based on a cubic model and without considering surface defects, the coercivity still cannot reach the theoretical value. It decreases with an increase in particle size, and the quasi-coherent and quasi-flower reversal modes appear continuously. Besides, surface defects do not affect the reversal mode, but they do decrease the coercivity and magnetic hardening effect, hence further amplifying the difference between coercivity and its theoretical value. The simulation results are strongly supported by experimental data. This study extensively examines the coercivity of M-type ferrite particles produced by various preparation methods, taking into account experimental observations and simulation results. Our findings can serve as guidance for the development of preparation technology for permanent magnet nanoparticles and contribute to a deeper understanding of the contradictions in coercivity and the mechanisms of magnetization reversal.
Keyword ：
Magnetization reversal mechanism Magnetization reversal mechanism Coercivity Coercivity Surface defects Surface defects Micromagnetic simulations Micromagnetic simulations Hexagonal ferrites Hexagonal ferrites
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| GB/T 7714 | Haseeb, M. , Li, Y. Q. , Zhang, H. G. et al. Influence and mechanism of surface defects on coercivity of M-type ferrite particles [J]. | SURFACES AND INTERFACES , 2024 , 46 . |
| MLA | Haseeb, M. et al. "Influence and mechanism of surface defects on coercivity of M-type ferrite particles" . | SURFACES AND INTERFACES 46 (2024) . |
| APA | Haseeb, M. , Li, Y. Q. , Zhang, H. G. , Liu, W. Q. , Zhang, P. J. , Yue, M. . Influence and mechanism of surface defects on coercivity of M-type ferrite particles . | SURFACES AND INTERFACES , 2024 , 46 . |
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