磁控溅射涂镀重稀土晶界扩散渗入钕铁硼磁体的能效分析

田广科; 张希; 崔光宇; 王瑜; 许亿; 夏原

doi:10.16490/j.cnki.issn.1001-3660.2025.16.019

PDF(3253 KB)

表面技术 ›› 2025, Vol. 54 ›› Issue (16) : 221-230. DOI: 10.16490/j.cnki.issn.1001-3660.2025.16.019

表面功能化

磁控溅射涂镀重稀土晶界扩散渗入钕铁硼磁体的能效分析

田广科^1,*, 张希¹, 崔光宇¹, 王瑜², 许亿³, 夏原³

作者信息 +

Efficacy of Magnetron Sputtered Heavy Rare Earth Grain Boundary Diffusion into Nd-Fe-B Permanent Magnets

TIAN Guangke^1,*, ZHANG Xi¹, CUI Guangyu¹, WANG Yu², XU Yi³, XIA Yuan³

Author information +

文章历史 +

摘要

目的采用Dy、Tb等重稀土元素晶界扩散是制备高性能钕铁硼磁材的重要技术手段,但现阶段工业化晶界扩散生产过程的工艺模式仍然较为粗放,对重稀土等国家战略性资源的极致利用还远不够精细。方法采用直流磁控溅射镀膜技术在牌号42SH钕铁硼磁体表面沉积约10 μm厚Tb涂层,然后在高真空扩散炉中对镀Tb磁体进行晶界扩散处理,研究了一步扩散法和梯度扩散法工艺模式变化对Tb渗入效率和提高磁体内禀矫顽力实际效能的影响,尝试性地建立了重稀土渗入效率、单位重稀土渗入量产生的实际效能、单位重稀土沉积量产生的实际效能的计算方法,结合电子探针分析了不同扩散模式下重稀土渗入磁体的分布特征。结果一步扩散法的重稀土渗入效率由86%提高到91%和95%,而梯度扩散法达到96%。梯度扩散法的单位浓度Tb渗入量的内禀矫顽力提升量可达到21.42 kOe/wt.%Tb,单位浓度Tb沉积量的内禀矫顽力提升量可达到20.5 kOe/wt.%Tb,换算成单位内禀矫顽力提升量需要的Tb沉积量则为0.049wt.%Tb/kOe,该指标可为不同内禀矫顽力提升量的生产需求预测出合理的重稀土沉积量。结论在梯度扩散模式下,有更多的Tb原子沿晶界相渗入至磁体更深位置,在更多的Nd₂Fe₁₄B主相晶粒表面形成具有更高磁晶各向异性场核壳结构(Nd,Tb)₂Fe₁₄B硬磁层,所以梯度扩散模式下矫顽力提升量最大。

Abstract

With the booming development of new energy automobiles and wind power generation, high remanent magnetism, high coercivity and high thermal stability of NdFeB magnets have reached tens of thousands of tons of annual market demands. The grain boundary diffusion process (GBDP) of heavy rare earth elements (HRE) such as Dy and Tb is an important technological means to meet the demand of the above high-performance Nd-Fe-B magnets. However, the utilization of HRE in the present GBDP production lines is still far from being fine enough and there is a lack of quantitative assessment in its efficacy.
In this work, DC magnetron sputtering coating technology is used to deposit a Tb film approximately 10 μm thick on the surface of grade 42SH Nd-Fe-B magnets, and then a high vacuum diffusion furnace is used to carry out grain boundary diffusion on the Tb-coated magnets. After optimizing the best one-step diffusion process parameters of 950 ℃×9 h, the effects of the different process modes of one-step vacuum diffusion with holding temperature at 750, 850 and 950 ℃ for 9 h and gradient vacuum diffusion with holding temperature at each of the three levels of temperature for 3 h on the enhancement of the magnets are investigated. Several quantitative equations such as the HRE infiltration efficiency into the magnet, the actual efficacy per unit of infiltrated HRE on the coercivity enhancement, the actual efficacy per unit of consumed HRE on the coercivity enhancement are defined, the corresponding values under different diffusion modes are calculated and compared. Meanwhile, the distribution characteristics of Tb infiltrating into the magnets under different diffusion modes are analyzed by electron probe microanalyzer (EPMA).
The results show that for one-step diffusion with the same holding time of 9 h, the Tb infiltration efficiency increases from 86% to 91% and 95% when the diffusion temperature increases from 750 ℃ to 850 ℃ and 950 °C, respectively, and the infiltration efficiency of Tb in the gradient diffusion mode is even higher, reaching 96%. In terms of the effect of magnetic properties enhancement by GBDP, the gradient diffusion mode is also the most significant. In the gradient diffusion mode, the coercivity enhancement per unit infiltrated Tb can reach 21.42 kOe/wt.%Tb, and the coercivity enhancement per unit deposited Tb can be 20.5 kOe/wt.%Tb, this means that per kOe of coercivity increase needs at least 0.049wt.% of Tb deposition.
The EPMA composition analysis shows that in the one-step diffusion even at higher temperature of 950 ℃, due to the simultaneous occurrence of Tb atoms diffusing along the grain boundary phases and into the main phase grains, the infiltrated Tb is prone to enrichment at the surface and shallow surface layers of the magnet, and resulting in a lower Tb content in the longitudinal depth of the magnets. But in the gradient diffusion mode, the staged holding at 750 ℃×3 h and 850 ℃×3 h helps the Tb atoms to diffuse firstly along the grain boundaries to the longitudinal position of the magnet, and then, undergoing the third stage of 950 ℃×3 h, forming a core-shell structure (Nd, Tb)₂Fe₁₄B hard magnetic layer with higher magnetic crystal anisotropy field around more main-phase grains located at the deeper position of the magnets, thus the coercivity enhancement in the gradient diffusion mode is the largest.

导出引用

田广科, 张希, 崔光宇, 王瑜, 许亿, 夏原. 磁控溅射涂镀重稀土晶界扩散渗入钕铁硼磁体的能效分析[J]. 表面技术. 2025, 54(16): 221-230 https://doi.org/10.16490/j.cnki.issn.1001-3660.2025.16.019

TIAN Guangke, ZHANG Xi, CUI Guangyu, WANG Yu, XU Yi, XIA Yuan. Efficacy of Magnetron Sputtered Heavy Rare Earth Grain Boundary Diffusion into Nd-Fe-B Permanent Magnets[J]. Surface Technology. 2025, 54(16): 221-230 https://doi.org/10.16490/j.cnki.issn.1001-3660.2025.16.019

中图分类号： TM273

参考文献

[1] ÇAKIR M F.ANN (Artificial Neural Network) Controlled Virtual Laboratory Design for NdFeB Magnet Production[J]. Tehnicki Vjesnik-Technical Gazette, 2021, 28(1): 334-339.
[2] DURÁN PERDOMO J F, PÉREZ ALCÁZAR G A, COLORADO H D, et al. Systematic Study of the Dependence of Magnetic and Structural Properties of Nd₂Fe₁₄B Powders on the Average Particle Size[J]. Journal of Rare Earths, 2020, 38(9): 961-968.
[3] ZHOU T J, QU P P, PAN W M, et al.Sintered NdFeB Magnets with Tb - Dy Double-Layer Core/Shell Structure Were Fabricated by Double Alloy Method and Grain Boundary Diffusion[J]. Journal of Alloys and Compounds, 2021, 856: 158191.
[4] LIU Z, HE J.Several Issues on the Development of Grain Boundary Diffusion Process for Nd-Fe-B Permanent Magnets[J]. Acta Metall Sin, 2021, 57(9): 1155-1170.
[5] KIM T H, SASAKI T T, OHKUBO T, et al.Microstructure and Coercivity of Grain Boundary Diffusion Processed Dy-Free and Dy-Containing NdFeB Sintered Magnets[J]. Acta Materialia, 2019, 172: 139-149.
[6] DAI Z M, LI K, WANG Z H, et al.Grain Boundary Diffusion Mechanism in Dy-Diffused Nd-Fe-B Sintered Magnets[J]. Journal of Physics D: Applied Physics, 2024, 57(30): 305004.
[7] YE Z X, ZHAO X T, LIU L, et al.Simultaneous Enhancement of Coercivity and Saturation Magnetization in High-Performance Anisotropic NdFeB Thick Films with a Dy Diffusion Layer[J]. Nanoscale, 2023, 15(46): 18775-18784.
[8] ZHAO D, LIU F G, GAO Y, et al.Dy Evolution and Coercivity Improvement Mechanism of Sintered NdFeB Magnets in Thermal Diffusion Process[J]. Journal of Magnetism and Magnetic Materials, 2022, 563: 169943.
[9] NAKAMURA H, HIROTA K, SHIMAO M, et al.Magnetic Properties of Extremely Small Nd-Fe-B Sintered Magnets[J]. IEEE Transactions on Magnetics, 2005, 41(10): 3844-3846.
[10] CHEN W, LUO J M, GUAN Y W, et al.Grain Boundary Diffusion of Dy Films Prepared by Magnetron Sputtering for Sintered Nd-Fe-B Magnets[J]. Journal of Physics D Applied Physics, 2018, 51(18): 185001.
[11] HUANG J B, HUANG M, WANG F, et al.Microstructure Optimization and Coercivity Enhancement of Sintered NdFeB Magnet by Grain Boundary Diffusion of Multicomponent Tb₆₀Pr₁₀Cu₁₀Al₁₀Zn₁₀ Films[J]. Materials, 2023, 16(8): 3131.
[12] ZHAN H, PENG C X, XUE Y Z, et al.Effect of Different Deposition Sequences on the Magnetic Properties of Sintered Nd-Fe-B Magnets Diffused with Multicomponent Tb-Cu Films[J]. Journal of Materials Research and Technology, 2023, 27: 3161-3169.
[13] ZHOU T J, YANG X X, WANG Q R, et al.Effect of Diffusing TbH3 on Magnetic, Corrosion and Mechanical Properties of NdFeB Magnet[J]. Journal of Alloys and Compounds, 2023, 968: 172079.
[14] CAO J L, CHEN S Y, YU Z G, et al.Benefit of Ni Addition in Dy-Co Diffusion Alloys for Enhancing the Coercivity and Corrosion Resistance of Sintered Nd-Fe-B Magnets[J]. Materials Research Bulletin, 2024, 180: 113048.
[15] PAN J, CAO S, LI Y H, et al.Enhancing the Grain Boundary Diffusion Efficiency of Tb for Nd-Fe-B Magnets Using Multi-Element Composite Diffusion Source[J]. Journal of Alloys and Compounds, 2024, 984: 174003.
[16] TANG J, HUANG W C, LI D.Improvements in Properties of NdFeB Magnets Obtained via Magnetron Sputtering and Thermal Diffusion[J]. Journal of Rare Earths, 2024, 42(9): 1710-1716.
[17] KIM T H, LEE S R, YUN S J, et al.Anisotropic Diffusion Mechanism in Grain Boundary Diffusion Processed Nd- Fe-B Sintered Magnet[J]. Acta Materialia, 2016, 112: 59-66.
[18] CAO X J, CHEN L, GUO S, et al.Effect of Rare Earth Content on TbF₃ Diffusion in Sintered Nd-Fe-B Magnets by Electrophoretic Deposition[J]. Scripta Materialia, 2017, 131: 24-28.
[19] CAO X J, CHEN L, GUO S, et al.Impact of TbF₃ Diffusion on Coercivity and Microstructure in Sintered Nd-Fe-B Magnets by Electrophoretic Deposition[J]. Scripta Materialia, 2016, 116: 40-43.
[20] SODERŽNIK M, KORENT M, KRISTINA Ž S, et al. High-Coercivity Nd-Fe-B Magnets Obtained with the Electrophoretic Deposition of Submicron TbF₃ Followed by the Grain-Boundary Diffusion Process[J]. Acta Materialia, 2016, 115: 278-284.
[21] YAN J H, WU Q, GE H L, et al.Electrodeposition of Dy and Its Grain Boundary Diffusion Behavior of Sintered NdFeB Magnets[J]. Materials Chemistry and Physics, 2024, 315: 128901.
[22] LI D S, SUZUKI S, KAWASAKI T, et al.Grain Interface Modification and Magnetic Properties of Nd-Fe-B Sintered Magnets[J]. Japanese Journal of Applied Physics, 2008, 47(10R): 7876.
[23] WATANABE N, ITAKURA M, KUWANO N, et al.Microstructure Analysis of Sintered Nd-Fe-B Magnets Improved by Tb-Vapor Sorption[J]. Materials Transactions, 2007, 48(5): 915-918.
[24] SCHWARZER S, PAWLOWSKI B, RAHMIG A, et al.Permanent Magnetic Thick Films from Remanence Optimized NdFeB-Inks[J]. Journal of Materials Science: Materials in Electronics, 2004, 15(3): 165-168.
[25] BAO X Q, ZHANG S J, YU H J, et al.The Effect of Pressure-Assisted Grain Boundary Diffusion on Magnetic Properties and Microstructure of Nd-Fe-B Magnet Using TbF₃ Prepared by Screen Printing[J]. Journal of Magnetism and Magnetic Materials, 2024, 592: 171758.
[26] 鲁飞, 刘树峰, 李慧, 等. 稀土合金扩散烧结钕铁硼磁体研究进展[J]. 材料导报, 2024, 38(16): 164-171.
LU F, LIU S F, LI H, et al.Review on Rare Earth Alloy Diffused NdFeB Magnet[J]. Materials Reports, 2024, 38(16): 164-171.
[27] SUN X J, LIN X, LUO Y, et al.Study on the Rheological Behaviors, Thixotropy, and Printing Characteristics of Screen Printing Slurry for Nd-Fe-B[J]. Materials, 2024, 17(18): 4626.
[28] WU H H, WANG Z J, LIU W Q, et al.Strategy for Co-Enhancement of Interface Adhesion and Coercivity of Nd-Fe-B Grain Boundary Diffusion Magnet: TbH3 Nanopowders Used in Screen Printing[J]. Journal of Magnetism and Magnetic Materials, 2024, 610: 172595.
[29] MING X, HAN X, WANG J H, et al.Comprehensively Improved Magnetic Performance of Nd-Fe-B Magnets with High-Efficiency Grain Boundary Diffusion of Heavy Rare Earth[J]. Vacuum, 2024, 222: 113003.
[30] MOURA P C, SÉRIO S. Recent Applications and Future Trends of Nanostructured Thin Films-Based Gas Sensors Produced by Magnetron Sputtering[J]. Coatings, 2024, 14(9): 1214.
[31] WANG Z W, NI J J, SONG B, et al.Effect of Post-Sinter Annealing on Structure and Coercivity of (Zr, Ti)-Doped Nd-Ce-Fe-B Magnets[J]. Journal of Alloys and Compounds, 2024, 990: 174479.
[32] 周寿增, 董清飞, 高学绪. 烧结钕铁硼稀土永磁材料与技术[M]. 北京: 冶金工业出版社, 2011: 150-151.
ZHOU S Z, DONG Q F, GAO X X.Sintered NdFeB Rare Earth Permanent Magnet Materials and Technology[M]. Beijing: Metallurgical Industry Press, 2011: 150-151.
[33] ZHANG X H, QIU W Q, XU Y X, et al.Diffusion Behavior Controlled Performance Enhancement of Nd-Fe-B Magnets Diffused by Tb-Ni Alloy at Various Temperatures[J]. Journal of Materials Science: Materials in Engineering, 2025, 20(1): 7.
[34] ZHONG S W, YANG M N, REHMAN S U, et al.Microstructure, Magnetic Properties and Diffusion Mechanism of DyMg Co-Deposited Sintered Nd-Fe-B Magnets[J]. Journal of Alloys and Compounds, 2020, 819: 153002.
[35] ZHAN H, PENG C X, WANG M, et al.Magnetic Properties and Microstructural Evolution of Sintered Nd-Fe-B Magnets via Tb-Pr-Ce-Cu Diffusion[J]. Materials Today Communications, 2025, 43: 111587.
[36] JIN Z H, DING G F, FAN X D, et al.Temperature- Dependent Microstructure and Magnetic Properties Evolution in the Sintered Nd-Fe-B Magnets with Pr-Al-Cu Diffusion[J]. Journal of Alloys and Compounds, 2022, 926: 166725.
[37] ZHONG K X, SHI D W, LIU Z M.Significant Coercivity Enhancement of Ga-Doped Sintered Nd-Fe-B Magnet by Grain Boundary Diffusion Perpendicular to the C-Axis[J]. Journal of Magnetism and Magnetic Materials, 2023, 581: 170963.
[38] ZHANG Y J, MA T Y, LIU X L, et al.Coercivity Enhancement of Nd-Fe-B Sintered Magnets with Intergranular Adding (Pr, Dy, Cu)-H$_x$ Powders[J]. Journal of Magnetism and Magnetic Materials, 2016, 399: 159-163.
[39] REN S Q, LI X, ZHANG Z H, et al.Tb Diffusion Induced Microstructural Evolution and Magnetic Responses of Multi-Main-Phase Nd-Dy-Fe-Ga-B Magnet[J]. Journal of Materials Research and Technology, 2025, 35: 5484-5496.
[40] ZENG H X, LIU Z W, LI W, et al.Significantly Enhancing the Coercivity of NdFeB Magnets by Ternary Pr-Al-Cu Alloys Diffusion and Understanding the Elements Diffusion Behavior[J]. Journal of Magnetism and Magnetic Materials, 2019, 471: 97-104.
[41] FAN W B, ZHOU B, HE J Y, et al.Magnetic Properties and Rare Earth Element Diffusion Behavior of Hot- Deformed Nanocrystalline Dual-Main-Phase Nd-Ce-Fe- B Magnets[J]. RSC Advances, 2023, 13(10): 6668-6675.
[42] SONG T T, WANG H H, TANG X, et al.The Effects of Nd-Rich Phase Distribution on Deformation Ability of Hydrogenation-Disproportionation-Desorption-Recombination Powders and Magnetic Properties of the Final Die-Upset Nd-Fe-B Magnets[J]. Journal of Magnetism and Magnetic Materials, 2019, 476: 194-198.
[43] LIU J, ZHANG J T, XU J Y, et al.Coercivity Enhancement and Microstructure Optimization of Nd-Fe-Co-B Magnets by Dy₇₀Al₁₀Cu₂₀ Grain Boundary Diffusion[J]. Intermetallics, 2024, 170: 108325.
[44] XIE Y H, CAO S, CAO X J, et al.Effect of Intergranular Phase Proportion in Sintered Nd-Fe-B Magnets on Subsequent Grain Boundary Diffusion Using Tb-Cu Alloy[J]. Journal of Alloys and Compounds, 2023, 931: 167562.