Grain boundary diffusion treatment of sintered NdFeB magnets by low cost La-Al-Cu alloys with various Al/Cu ratios

Zeng, H.; Wang, Q.X.; Zhang, J.S.; Liao, Xuefeng; Zhong, Xichun; Yu, Hongya; Liu, Z.W.

doi:10.1016/j.jmmm.2019.165498

Cited by 38 publications

(5 citation statements)

References 30 publications

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“…The GBD conditions of LRE sources are similar to those of the HRE sources, i.e., using a two-step heat treatment process. At present, the effective LRE-based diffusion sources mainly include Pr-and Nd-based low-melting alloys [30][31][32][33][34][35][36]. The coercivity increment caused by Pr-Al-Cu reaches 700 kA/m and~500 kA/m for 2 mm-and 10 mm-thick magnets, respectively [33].…”

Section: Development Of Diffusion Sources and Their Fabricationmentioning

confidence: 99%

“…The coercivity increment caused by Pr-Al-Cu reaches 700 kA/m and~500 kA/m for 2 mm-and 10 mm-thick magnets, respectively [33]. In addition to the Pr-and Nd-based diffusion alloys, high-abundance La-and Ce-based alloys have been also studied as diffusion sources recently [34][35][36]. However, their caused coercivity enhancement is still marginal.…”

Section: Development Of Diffusion Sources and Their Fabricationmentioning

confidence: 99%

“…The diffusion of Pr70Al20Cu10 alloy can lead to an Hcj increase o 712 kA/m, much higher than that caused by Pr70Al10Cu20 diffusion (360 kA/m). A simila phenomenon can be observed in the La-Al-Cu system [34]. Therefore, the selection of non RE alloying elements is very important for designing effective LRE-M diffusion source Furthermore, the non-RE elements such as Al and Ni can also modify the 2:14:1 phase b substituting Fe for a higher HA [16].…”

Section: Design Of Lre-based Diffusion Sourcesmentioning

confidence: 99%

“…This indicates that the critical RE elements may be not necessary for GBD. The reported non-RE based diffusion sources includes compounds and metals/alloys [34][35][36]. Although their positive effects on coercivity enhancement are still weaker than those of RE-based sources, it was found interesting that the diffusion of non-RE elements is effective to improve the chemical stability of the magnets [34][35][36].…”

Section: Design Of Non-re-based Diffusion Sourcesmentioning

confidence: 99%

“…The reported non-RE based diffusion sources includes compounds and metals/alloys [34][35][36]. Although their positive effects on coercivity enhancement are still weaker than those of RE-based sources, it was found interesting that the diffusion of non-RE elements is effective to improve the chemical stability of the magnets [34][35][36]. The existing results imply that the non-RE GBD could have a broader application range than the RE GBD.…”

Section: Design Of Non-re-based Diffusion Sourcesmentioning

confidence: 99%

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Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets

Cao

et al. 2021

Metals

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Nd-Fe-B magnets containing no heavy rare earth (HRE) elements exhibit insufficient coercivity to withstand the demagnetization field at elevated temperatures. The grain boundary diffusion (GBD) process provides the best route to fabricate high-coercive Nd-Fe-B magnets with low consumption of expensive HRE resources. Here we give a special review on the grain boundary diffusion sources and their coating methods. Up to now, various types of grain boundary sources have been developed, starting from the earliest Tb or Dy metal. The HRE-M eutectic alloys were firstly proposed for reducing the cost of the diffusion source. After that, the diffusion sources based on light rare earth and even non rare earth elements have also been proposed, leading to new understanding of GBD. Now, the diffusion sources including inorganic compounds, metals, and alloys have been employed in the industry. At the same time, to coat the diffusion source on the magnets before diffusion treatment, various methods have been developed. Different from the previous review articles for GBD, this review gives an introduction of typical types of diffusion sources and their fabrication approaches. The effects of diffusion source on the microstructure and magnetic properties are summarized briefly. In particular, the principles and applicability of different coating approaches were discussed in detail. It is believed that this review can provide a technical guidance for the industry for designing the diffusion process and products meeting specific requirements.

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Section: Development Of Diffusion Sources and Their Fabricationmentioning

confidence: 99%

Section: Development Of Diffusion Sources and Their Fabricationmentioning

confidence: 99%

Section: Design Of Lre-based Diffusion Sourcesmentioning

confidence: 99%

Section: Design Of Non-re-based Diffusion Sourcesmentioning

confidence: 99%

Section: Design Of Non-re-based Diffusion Sourcesmentioning

confidence: 99%

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Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets

Cao

et al. 2021

Metals

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Understanding the Role of Element Grain Boundary Diffusion Mechanism in Nd–Fe–B Magnets

Zhao

et al. 2021

Adv Funct Materials

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Grain boundary diffusion (GBD) of multiple rare earths has proven effective in enhancing the performance of permanent magnets, whereas the diffusion behaviors are still unclear due to their intricate interactions. In this work, the synergistic effects of three rare earths (Tb, Ce, and La) on the grain boundaries diffusion process are investigated, achieving a high‐performance diffused Nd–Fe–B magnet with the high coercivity of 1822 kA m−1 and thermal stability of −0.447% K−1. This promotion originates from the improved diffusion depth of Tb at specific regions, induced by the coordination effects of Ce and La, as evidenced via electron probe microanalysis and the first‐principles calculations. It thus results in the uniform formation of Tb‐diffused magnetic harden grains, associated with the strongly pinned domain walls, which is further observed directly by in situ Lorentz transmission electron microscopy and reconstructed by micromagnetic simulations. The study provides insight into the role of element GBD mechanism and has promising potential to explore other element systems as diffusion sources for permanent magnets.

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Improved magnetic properties of Sr0.93Sm0.10Fe11.97O19/Fe3O4 composite powders by substitution of Sm and magnetic exchange coupling effect

Liang

et al. 2020

J Mater Sci: Mater Electron

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Grain boundary diffusion treatment of sintered NdFeB magnets by low cost La-Al-Cu alloys with various Al/Cu ratios

Cited by 38 publications

References 30 publications

Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets

Grain Boundary Diffusion Sources and Their Coating Methods for Nd-Fe-B Permanent Magnets

Understanding the Role of Element Grain Boundary Diffusion Mechanism in Nd–Fe–B Magnets

Improved magnetic properties of Sr0.93Sm0.10Fe11.97O19/Fe3O4 composite powders by substitution of Sm and magnetic exchange coupling effect

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