Boundary optimization and coercivity enhancement of high ( BH ) max Nd-Fe-B magnet by diffusing Pr-Tb-Cu-Al alloys

Lu, Kening; Bao, Xiaoqian; Tang, Minghui; Chen, Guixian; Mu, Xing; Li, Jiheng; Gao, Xuexu

doi:10.1016/j.scriptamat.2017.05.048

Cited by 85 publications

(13 citation statements)

References 23 publications

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“…The reported HRE-based diffusion sources can enhance the H cj by > 900 kA/m for the magnets with a thickness of <5 mm. The effective HRE containing GBD sources mainly include fluorides, hydrides, and metals/alloys [20][21][22][23][24][25][26][27][28][29].…”

Section: Development Of Diffusion Sources and Their Fabricationmentioning

confidence: 99%

“…However, it has been reported that Dy and Tb have a higher diffusion rate than their fluorides due to the different reactions occurring in the GB phase, and thus perform better in coercivity enhancement [45]. For achieving higher efficiency, the metallic HRE can be alloyed by LRE elements of Pr, Nd, La, and Ce, and non-RE elements of Al, Cu, Mg, etc., to form eutectic alloys with low melting points [26,28,32,[45][46][47]. These added elements also play important roles in enhancing the coercivity through thickening the GBs for magnetic decoupling or reducing the defects at the interface to hinder the nucleation of reversed domains.…”

Section: Hre-based Diffusion Sources and Their Fabricationmentioning

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: Hre-based Diffusion Sources and Their Fabricationmentioning

confidence: 99%

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

Cao

et al. 2021

Metals

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“…In recent years, the main interest in GBD is to develop high-efficiency diffusion sources to achieve the deep infiltration of HREs and high coercivity enhancement. Various types of diffusion sources, such as inorganic compounds, [12][13][14] metals, 15 and alloys, [16][17][18][19][20] have been developed.…”

Section: Introductionmentioning

confidence: 99%

Rationally selecting the chemical composition of the Nd–Fe–B magnet for high-efficiency grain boundary diffusion of heavy rare earths

Cao

et al. 2022

J. Mater. Chem. C

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“…In addition, the non-rare-earth elements Al/Ga/Cu can also increase the H cj of the sintered Nd-Fe-B magnets and reduce the irreversible loss of magnetic flux. These elements mainly enrich in the RE-rich (Rare-earth rich) liquid phase to improve the wettability and increase the coercivity of the magnets [ 17 , 18 , 19 ]. Therefore, we select the ternary alloy Pr 70 Al 10 Ga 20 and Dy 70 Al 10 Ga 20 and quaternary alloy (Pr 75 Dy 25 ) 70 Al 10 Ga 20 as the diffusion sources in this work.…”

Section: Introductionmentioning

confidence: 99%

Optimized Microstructure and Improved Magnetic Properties of Pr-Dy-Al-Ga Diffused Sintered Nd-Fe-B Magnets

Rehman

et al. 2021

Materials

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The grain boundary diffusion process (GBDP) has become an important technique in improving the coercivity and thermal stability of Dy-free sintered Nd-Fe-B magnets. The influence of Dy70Al10Ga20 and (Pr75Dy25)70Al10Ga20 alloys by the GBDP on sintered Nd-Fe-B magnets are investigated in this paper. After diffusing Dy70Al10Ga20 and (Pr75Dy25)70Al10Ga20 alloys, the coercivity (Hcj) of the magnets increased from 13.58 kOe to 20.10 kOe and 18.11 kOe, respectively. Meanwhile, the remanence of the magnets decreased slightly. The thermal stability of the diffused magnets was improved by the GBDP. The microstructure shows continuous Rare-earth-rich (RE-rich) grain boundary phases and (Dy, Pr/Nd)2Fe14B core-shell structures which contribute to improving the coercivity. Moreover, the Dy concentration on the surface of the (Pr75Dy25)70Al10Ga20 diffused magnets decreased with the Pr substitution for the Dy element. The openness of the recoil loops for the (Pr75Dy25)70Al10Ga20 diffused magnets is smaller than that of the original magnets and Dy70Al10Ga20 diffused magnets. The results show that the (Pr75Dy25)70Al10Ga20 alloys can effectively optimize the microstructure and improve the magnetic properties and thermal stability of the sintered Nd-Fe-B magnets.

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Boundary optimization and coercivity enhancement of high ( BH ) max Nd-Fe-B magnet by diffusing Pr-Tb-Cu-Al alloys

Cited by 85 publications

References 23 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

Rationally selecting the chemical composition of the Nd–Fe–B magnet for high-efficiency grain boundary diffusion of heavy rare earths

Optimized Microstructure and Improved Magnetic Properties of Pr-Dy-Al-Ga Diffused Sintered Nd-Fe-B Magnets

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