Nd90Al10 晶界调控对晶界扩散磁体磁性能和微观结构的影响

doi:10.11900/0412.1961.2021.00471

金属学报

2023, Vol. 59

Issue (11): 1457-1465 DOI: 10.11900/0412.1961.2021.00471

本期目录 | 过刊浏览

Nd₉₀Al₁₀ 晶界调控对晶界扩散磁体磁性能和微观结构的影响

刘路军¹, 刘政²(

), 刘仁辉³, 刘永¹

^1.江西理工大学材料与冶金学部赣州 341000
^2.江西理工大学机电工程学院赣州 341000
^3.江西理工大学江西省稀土磁性材料及器件重点实验室赣州 341000

Grain Boundary Structure and Coercivity Enhancement of Nd₉₀Al₁₀ Alloy Modified NdFeB Permanent Magnets by GBD Process

LIU Lujun¹, LIU Zheng²(

), LIU Renhui³, LIU Yong¹

^1.Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, China
^2.School of Mechanical and Electronical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
^3.Jiangxi Key Laboratory for Rare Earth Magnetic Material and Devices, Jiangxi University of Science and Technology, Ganzhou 341000, China

引用本文:

刘路军, 刘政, 刘仁辉, 刘永. Nd₉₀Al₁₀ 晶界调控对晶界扩散磁体磁性能和微观结构的影响[J]. 金属学报, 2023, 59(11): 1457-1465.
Lujun LIU, Zheng LIU, Renhui LIU, Yong LIU. Grain Boundary Structure and Coercivity Enhancement of Nd₉₀Al₁₀ Alloy Modified NdFeB Permanent Magnets by GBD Process[J]. Acta Metall Sin, 2023, 59(11): 1457-1465.

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摘要:

采用添加Nd₉₀Al₁₀低熔点合金调控制备了扩散用烧结Nd₂Fe₁₄B磁体，并采用Tb晶界扩散制备了相应的扩散磁体，分析了扩散磁体的晶界结构和成分对磁体矫顽力的影响。结果表明，添加质量分数为0.5%的Nd₉₀Al₁₀合金调控后，晶界扩散(GBD)后磁体的矫顽力提高到1439 kA/m，相对于未晶界调控的扩散磁体增加了530 kA/m。添加Nd₉₀Al₁₀低熔点合金不会影响GBD前磁体的Curie温度，但降低了磁体的低温相变温度。GBD后磁体Tb取代晶格中的Nd引起Nd₂Fe₁₄B相的晶格常数减小，从而使XRD谱中衍射峰位右移。经Nd₉₀Al₁₀调控后的扩散磁体表面处的主相晶粒的富Tb壳清晰可见。从距离磁体表面20 μm增加到100 μm时，富Tb壳层仍清晰可见。当深度继续增加到500 μm时，经Nd₉₀Al₁₀调控后的扩散磁体晶粒周围都有连续晶界相。经晶界调控的扩散磁体可见衬度明显的富Tb壳层，形成了非晶的富Nd相，增强了两两主相晶粒间的去磁耦合能力。Nd在富Nd相中心区域出现峰值，更多的富Nd相在晶界扩散过程中作为Tb向磁体内扩散的通道，Tb原子在富Nd相的浓度高达约35%，其扩散深度和使用效率明显提升。

关键词 ：烧结钕铁硼, 晶界扩散, 磁性能, 晶界调控

Abstract：

The grain boundary diffusion (GBD) process is a remarkable achievement in sintered Nd-Fe-B permanent magnet manufacturing. Furthermore, the coercivity can be considerably improved by diffusing heavy rare earth (HRE) elements into the magnet along the grain boundary, and the reduced HRE consumption can also be realized. However, compared with parameters of GBD, previous research has focused less on improving the magnet. In this study, the magnet was prepared using low melting point alloy Nd₉₀Al₁₀ before GBD modification, after which the corresponding Tb-GBD was completed. The magnetic property results indicated that the coercivity increased to 1439 kA/m, which was 530 kA/m higher than the unmodified magnet. Thus, the effects of the grain boundary structure and composition on the coercivity were analyzed. The addition of Nd₉₀Al₁₀ did not affect the Curie temperature of the magnet, but it reduced the low-temperature phase transition temperature. The Tb replaced Nd at the margin of main phase, which moved the diffraction peak to the right in the XRD spectrum. Moreover, a clear Tb-rich shell surrounding the main phase formed in the diffused magnet modified by Nd₉₀Al₁₀ at the depth of 20 μm, and the shell could still be clearly observed at 100 μm. However, the main phase was surrounded by the continuous grain boundary when the depth increased to 500 μm in Nd₉₀Al₁₀ modified magnet by GBD. The Tb-rich shell was observed by TEM and a noncrystalline Nd-rich phase was observed. The content peak of the Nd element appeared in the central region of the Nd-rich phase. This, the diffused depth and usage efficiency remarkably improved, because the Nd-rich phase acted as a channel for Tb diffusion, with the concentration of Tb being as high as 35%.

Key words： sintered Nd-Fe-B magnet grain boundary diffusion coercivity grain boundary modification

收稿日期: 2021-11-01

ZTFLH:

TM273

基金资助:国家高技术研究发展计划项目(2010AA03A0401)

通讯作者: 刘政，liukk66@163.com，主要从事材料成形方面的研究

Corresponding author: LIU Zheng, professor, Tel: 13879729585, E-mail: liukk66@163.com

作者简介: 刘路军，男，1982年生，博士生

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图1 原始合金和晶界调控磁体的DSC曲线

图2 A0和AMG磁体的XRD谱及59°~62°区间的局部放大图

图3 A0、AG、AMG磁体的磁性能

图4 AG和AMG磁体距表面不同深度的微观形貌

图5 AMG磁体的高角环形暗场(HAADF)像及选区电子衍射(SAED)花样

图6 AG和AMG磁体的SEM像及富Nd相中的元素分布

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