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Journal of Chinese Society for Corrosion and protection  2025, Vol. 45 Issue (4): 1117-1126    DOI: 10.11902/1005.4537.2024.288
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Preparation and Corrosion Resistance of Surface Mg-alloying NdFeB Magnets
RAN Renhao1, SHAN Huilin1, ZHANG Pengjie2, WANG Dongmei1,3, SI Jiajia1,3, XU Guangqing1,3(), LV Jun1,3
1 School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China
2 BGRIMM Magnetic Materials and Technology Co., Ltd., Beijing 102600, China
3 Key Laboratory of Advanced Functional Materials and Devices of Anhui Province, Engineering Research Center of High Performance Copper Alloy Materials and Processing, Ministry of Education, National-Local Joint Engineering Research Center of Nonferrous Metals and Processing Technology, Hefei 230009, China
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RAN Renhao, SHAN Huilin, ZHANG Pengjie, WANG Dongmei, SI Jiajia, XU Guangqing, LV Jun. Preparation and Corrosion Resistance of Surface Mg-alloying NdFeB Magnets. Journal of Chinese Society for Corrosion and protection, 2025, 45(4): 1117-1126.

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Abstract  

NdFeB magnets of poor corrosion resistance was subjected to surface Mg-alloying via magnetron sputtering technique and followed by thermal diffusion treatment, so that to improve the corrosion resistance of the magnets. The corrosion resistance of the surface Mg alloying NdFeB magnets in 3.5%NaCl solution is investigated by static immersion test corrosion electrochemical measurements and accelerated aging tests to optimize the preparation parameters of the surface Mg alloying. The surface Mg alloying NdFeB magnets before and afer corrosion test are characterized by X-ray diffractometer, X-ray photoelectron spectrometer and scanning electron microscope, as well as by atomic force microscope for determining the potential difference between the phases within the magnets during corrosion process. Results show that the magnets subjected to Mg-sputtering and then diffusion treated at 550 ℃ for 105 min shows the best corrosion resistance, with Ecorr of -0.684 V and Icorr of 1.055 × 10-6 A·cm-2, which is an order of magnitude lower than that of the bare magnets (6.896 × 10-5 A·cm-2). The mechanism related with the enhancement of corrosion resistance may be that the Mg atoms diffuse into the intergranular of the magnets, stabilizing the Nd-rich phase in grain boundaries and relieving the potential difference between the matrix and the intergranular, thus reducing the free-corrosion tendency of NdFeB magnets.
Key words:  NdFeB      surface Mg alloying      magnetron sputtering      grain boundary diffusion      corrosion resistance     
Received:  05 September 2024      32134.14.1005.4537.2024.288
ZTFLH:  TG174  
Fund: National Key Research and Development Program(2022YFB3504800)
Corresponding Authors:  XU Guangqing, E-mail: gqxu1979@hfut.edu.cn
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RAN Renhao
SHAN Huilin
ZHANG Pengjie
WANG Dongmei
SI Jiajia
XU Guangqing
LV Jun

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https://www.jcscp.org/EN/10.11902/1005.4537.2024.288     OR     https://www.jcscp.org/EN/Y2025/V45/I4/1117

Fig.1  XRD patterns of NdFeB and NdFeB(Mg) treated under different conditions (a) and polished NdFeB(Mg)-550-105 specimen (b)
Fig.2  XPS survey spectra of NdFeB, Mg/NdFeB, NdFeB(Mg)-550-105 and NdFeB(Mg)-550-105-m specimens (a), and corresponding high resolution patterns of Mg 1s (b)
Fig.3  SEM cross-sectional morphologies and EDS analysis results of Mg/NdFeB (a), NdFeB(Mg)-500-105 (b), NdFeB(Mg)-550-105 (c), NdFeB(Mg)-600-105 (d), NdFeB(Mg)-550-90 (e) and NdFeB(Mg)-550-120 (f)
Fig.4  TEM image of NdFeB(Mg)-550-105 specimen (a), enlarged images (b, e), element mappings (c, f) and selected-area electron diffraction patterns (d, g) of the regions A and B marked in Fig.4a, respectively
Fig.5  Optical photos of NdFeB (a), NdFeB(Mg)-550-90 (b), NdFeB(Mg)-550-105 (c), NdFeB(Mg)-550-120 (d), NdFeB(Mg)-500-105 (e) and NdFeB(Mg)-600-105 (f) after static full-immersion corrosion tests for different time
Fig.6  Potentiodynamic polarization curves (a) and impedance profiles (b) of NdFeB and various NdFeB(Mg) specimens
SpecimensEcorr / VIcorr / A·cm-2Rs / Ω·cm2Rct / Ω·cm2
NdFeB-0.9146.896 × 10-57.768836
NdFeB(Mg)-500-105-0.8012.342 × 10-57.5656840
NdFeB(Mg)-550-105-0.6841.055 × 10-67.82318335
NdFeB(Mg)-600-105-0.7637.068 × 10-67.86810558
NdFeB(Mg)-550-90-0.7539.661 × 10-67.6588550.8
NdFeB(Mg)-550-120-0.7194.032 × 10-68.00811670
NdFeB(Mg)-550-105-m-0.7682.513 × 10-57.9215254
Table 1  Ecorr, Icorr, Rs and Rct values of NdFeB and various NdFeB(Mg) specimens
Fig.7  Mass gains of NdFeB and NdFeB(Mg) specimens after accelerated ageing test for 500 h
SpecimensMG / mg·cm-2VG / mg·cm-2·h-1
NdFeB0.601.20 × 10-3
NdFeB(Mg)-500-1050.511.02 × 10-3
NdFeB(Mg)-550-1050.340.68 × 10-3
NdFeB(Mg)-600-1050.450.9 × 10-3
NdFeB(Mg)-550-900.440.88 × 10-3
NdFeB(Mg)-550-1200.390.78 × 10-3
Table 2  MG and VG values of NdFeB and various NdFeB(Mg) specimens
Fig.8  XPS total spectra (a) and high resolution spectra of Mg 1s (b) for NdFeB and NdFeB(Mg)-550-105 before and after corrosion
Fig.9  AFM surface potentials of NdFeB (a) and NdFeB(Mg)-550-105 (b)
[1] Junne T, Wulff N, Breyer C, et al. Critical materials in global low-carbon energy scenarios: the case for neodymium, dysprosium, lithium, and cobalt [J]. Energy, 2020, 211: 118532
[2] Coey J M D. Permanent magnet applications [J]. J. Magn. Magn. Mater., 2002, 248: 441
[3] Ni J J, Zhou S T, Jia Z F, et al. Improvement of corrosion resistance in Nd-Fe-B sintered magnets by intergranular additions of Sn [J]. J. Alloy. Compd., 2014, 588: 558
[4] Assis O B G, Sinka V, Ferrante M, et al. Electrochemical aspects of corrosion in sintered and hot-deformed Nd-Fe-B magnets [J]. J. Alloy. Compd., 1995, 218: 263
[5] Liu W Q, Yue M, Zhang D T, et al. Electrochemical corrosion behavior of Nd-Fe-B permanent magnets with modified microstructure [J]. J. Appl. Phys., 2009, 105: 07A709
[6] Liu W Q, Yue M, Zhang J X, et al. Intrinsic corrosion characteristic of sintered NdFeB permanent magnets [J]. Powder Metall. Technol., 2006, 24: 195
(刘卫强, 岳 明, 张久兴 等. 烧结NdFeB永磁合金本征腐蚀特性研究进展 [J]. 粉末冶金技术, 2006, 24: 195)
[7] Li Z J, Wang X E, Li J Y, et al. Effects of Mg nanopowders intergranular addition on the magnetic properties and corrosion resistance of sintered Nd-Fe-B [J]. J. Magn. Magn. Mater., 2017, 442: 62
[8] Cui X G, Yan M, Ma T Y, et al. Effects of Cu nanopowders addition on magnetic properties and corrosion resistance of sintered Nd-Fe-B magnets [J]. Physica, 2008, 403B: 4182
[9] Nakamura H, Hirota K, Shimao M, et al. Magnetic properties of extremely small Nd-Fe-B sintered magnets [J]. IEEE Trans. Magn., 2005, 41: 3844
[10] Zhang P, Ma T Y, Liang L P, et al. Improvement of corrosion resistance of Cu and Nb co-added Nd-Fe-B sintered magnets [J]. Mater. Chem. Phys., 2014, 147: 982
[11] Kim A S, Camp F E, Dulis E J. Effect of oxygen, carbon, and nitrogen contents on the corrosion resistance of Nd-Fe-B magnets [J]. IEEE Trans. Magn., 1990, 26: 1936
[12] Ni J J, Ma T Y, Cui X G, et al. Improvement of corrosion resistance and magnetic properties of Nd-Fe-B sintered magnets by Al85Cu15 intergranular addition [J]. J. Alloy. Compd., 2010, 502: 346
[13] Zhang P, Ma T Y, Liang L P, et al. Improved corrosion resistance of low rare-earth Nd-Fe-B sintered magnets by Nd6Co13Cu grain boundary restructuring [J]. J. Magn. Magn. Mater., 2015, 379: 186
[14] Zhou Q, Liu Z W, Zhong X C, et al. Properties improvement and structural optimization of sintered NdFeB magnets by non-rare earth compound grain boundary diffusion [J]. Mater. Des., 2015, 86: 114
[15] Wang E H, Xiao C H, He J Y, et al. Grain boundary modification and properties enhancement of sintered Nd-Fe-B magnets by ZnO solid diffusion [J]. Appl. Surf. Sci., 2021, 565: 150545
[16] Li M J, Sun X F, Guan H R, et al. High temperature hot-corrosion behavior of (Ni, Pd)Al coating [J]. Acta Metall. Sin., 2004, 40: 773
(李猛进, 孙晓峰, 管恒荣 等. (Ni, Pd)Al涂层的高温热腐蚀 [J]. 金属学报, 2004, 40: 773)
[17] Qu Z J, Wu Q, Zhang M K, et al. Facile preparation of bonded NdFeB/SmFeN hybrid magnets with flexibility, anisotropy and high energy density [J]. J. Magn. Magn. Mater., 2023, 584: 171084
[18] Yates K, West R H. Monochromatized Ag Lα X‐rays as a source for higher energy XPS [J]. Surf. Interf. Anal., 1983, 5: 133
[19] Seyama H, Soma M. X-ray photoelectron spectroscopic study of montmorillonite containing exchangeable divalent cations [J]. J. Chem. Soc. Faraday Trans. 1: Phys. Chem. Condens. Phases, 1984, 80: 237
[20] Wagner C D. Studies of the charging of insulators in ESCA [J]. J. Electron. Spectrosc. Relat. Phenom., 1980, 18: 345
[21] Dai J L, Yang Z X, Liu Q. Rare earth cerium increases the corrosion resistance of NdFeB magnets [J]. Materials, 2020, 13: 4360
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