Issue 2, 2023

Tb–Cu grain boundary diffusion effects on single- and multi-main-phase Nd–Fe–B based magnets

Abstract

Grain boundary diffusion (GBD) has been widely employed in single-main-phase (SMP) Nd–Fe–B magnets for coercivity enhancement. However, for cost-effective multi-main-phase (MMP) magnets, the GBD process has not been well developed. Here, we carry out a systematic study to compare the different element diffusion and demagnetization behaviors in Tb–Cu diffused SMP and MMP magnets. The SMP magnets contain only (Nd,Pr)-based hard magnetic grains, whereas MMP magnets contain both (Nd,Pr,Dy)-based and (Ce,La,Nd,Pr,Dy)-based hard magnetic grains. The results suggest that although the infiltration of Tb is deeper in MMP magnets than in SMP magnets, the coercivity enhancement for MMP magnets is much less than that for SMP magnets. After GBD treatment, the magnetic hysteresis loop squareness of MMP magnets is seriously destroyed, resulting in a low energy product. The deep diffusion of Tb in MMP magnets is mainly attributed to the low melting point of the Ce-rich intergranular phase, which can act as the diffusion channel for the Tb–Cu alloy. However, the strong inter-diffusion between the two main phases in the MMP magnets that occurred during the GBD treatment results in composition homogenization, which is not beneficial to the coercivity and the hysteresis loop squareness. The micromagnetic simulations reveal that the large difference in HA between the surface and the center of the MMP magnets after composition homogenization by GBD is the main reason for the non-concurrent magnetic reversal and the poor loop squareness. The different GBD effects on the microstructure and magnetic properties of SMP and MMP Nd–Fe–B based magnets obtained in this work may help in further optimizing their GBD process.

Graphical abstract: Tb–Cu grain boundary diffusion effects on single- and multi-main-phase Nd–Fe–B based magnets

Article information

Article type
Paper
Submitted
23 Jul 2022
Accepted
05 Dec 2022
First published
19 Dec 2022

J. Mater. Chem. C, 2023,11, 645-655

Tb–Cu grain boundary diffusion effects on single- and multi-main-phase Nd–Fe–B based magnets

Z. Yu, X. Liu, J. He, J. Cao, W. Fan, Y. Wu, H. Yu, Z. Liu, Z. Wang and E. Niu, J. Mater. Chem. C, 2023, 11, 645 DOI: 10.1039/D2TC03090J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements