Comparison of microstructures and magnetic properties of Tb-Pr-Cu-Al and Tb-Nd-Cu-Al grain boundary diffused Nd-Fe-B magnets

Zixiang Mo; Qingzheng Jiang; Mengping Kan; Jianming Li; Hang Wang

Journal of Materials Research and Technology (Mar 2025)

Comparison of microstructures and magnetic properties of Tb-Pr-Cu-Al and Tb-Nd-Cu-Al grain boundary diffused Nd-Fe-B magnets

Zixiang Mo,
Qingzheng Jiang,
Mengping Kan,
Jianming Li,
Hang Wang

Affiliations

Zixiang Mo: Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China
Qingzheng Jiang: Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China; Guorui Kechuang Rare Earth Functional Materials (Ganzhou) Co., Ltd, National Rare Earth Functional Materials Innovation Center, Ganzhou, 341000, PR China; Zhejiang Innuovo Magnetics Co., Ltd, Jinhua 321000, PR China; Corresponding author. Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China.
Mengping Kan: Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China
Jianming Li: Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China
Hang Wang: Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China; Guorui Kechuang Rare Earth Functional Materials (Ganzhou) Co., Ltd, National Rare Earth Functional Materials Innovation Center, Ganzhou, 341000, PR China; Corresponding author. Jiangxi Provincial Key Laboratory of Magnetic Metallic Materials and Devices & College of Rare Earths, Jiangxi University of Science and Technology, Ganzhou, 341000, PR China.

Journal volume & issue: Vol. 35
pp. 1865 – 1874

Abstract

Read online

Low melting alloys containing heavy rare earth element Tb have been widely used for grain boundary diffusion (GBD) to increase the coercivity (Hcj) of sintered Nd-Fe-B magnets. The addition of Pr has been demonstrated to further enhance the coercivity for Tb-diffused magnets. With chemical properties similar to Pr, Nd can also substitute for Tb, contributing to a further reduction in heavy rare earth content in diffusion sources. However, the differences between Pr and Nd in influencing Tb diffusion behavior have not been fully explored. This paper systematically compared the magnetic properties and microstructure of TbxNd70-xAl20Cu10 (x = 10, 30, 50, 70, at%) and TbxPr70-xAl20Cu10 (x = 10, 30, 50, 70, at%) diffused magnets, with a focusing on the effects of Pr and Nd substitution on Tb diffusion depth, diffusion coefficient, and Tb content in the shell layer. After diffusion with Tb30Nd40Al20Cu10, the coercivity increased significantly from 15.87 kOe to 24.86 kOe, with a coercivity temperature coefficient of −0.491 %/°C at the range of 20–150 °C. Compared with TbxPr70-xAl20Cu10 diffused magnets, Tb shows greater diffusion depth and diffusion coefficient, along with a thick Tb-rich shell around the main phase grains in TbxNd70-xAl20Cu10 diffused magnet. However, for diffusion sources with low Tb content, Tb-Pr-Cu-Al diffused magnets exhibited superior coercivity due to the high Pr content in the main phase grains and the formation of continuous thin grain boundary layer.

Published in Journal of Materials Research and Technology

ISSN: 2238-7854 (Print); 2214-0697 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Technology: Mining engineering. Metallurgy
Website: https://www.journals.elsevier.com/journal-of-materials-research-and-technology/

About the journal

Abstract

Keywords