Sintered NdFeB magnets with Tb - Dy double-layer core/shell structure were fabricated by double alloy method and grain boundary diffusion

2021 ◽  
Vol 856 ◽  
pp. 158191
Author(s):  
Toujun Zhou ◽  
Pengpeng Qu ◽  
Weimao Pan ◽  
Renhui Liu ◽  
Mianfu Li ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Double Layer ◽  
Shell Structure ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Core Shell ◽  
Ndfeb Magnets ◽  
Core Shell Structure

scholarly journals Nd-Fe-B Magnets: The Gradient Change of Microstructures and the Diffusion Principle after Grain Boundary Diffusion Process

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3881 ◽  
Author(s):  
Yaojun Lu ◽  
Shuwei Zhong ◽  
Munan Yang ◽  
Chunming Wang ◽  
Liuyimei Yang ◽  
...  
Keyword(s):  
Surface Layer ◽  
Grain Boundary ◽  
Diffusion Process ◽  
Shell Structure ◽  
Boundary Diffusion ◽  
Diffusion Mechanism ◽  
Temperature Stability ◽  
Grain Boundary Diffusion ◽  
Core Shell ◽  
Core Shell Structure

The diffusion of Tb in sintered Nd-Fe-B magnets by the grain boundary diffusion process can significantly enhance coercivity. However, due to the influence of microstructures at different depths, the coercivity increment and temperature stability gradually decreases with the increase of diffusion depth, and exhibit good corrosion resistance at a sub-surface layer (300–1000 μm). According to the Electron Probe Micro-analyzer (EPMA) test results and the diffusion mechanism, the grain boundary and intragranular diffusion behavior under different Tb concentration gradients were analyzed, and the diffusion was divided into three stages. The first stage is located on the surface of the magnet, which formed a thick core-shell structure and a large number of RE-rich phases. The second stage is located in the sub-surface layer, forming a uniform and continuous RE-rich phase and thin core-shell structure. The third stage is located deeper in the magnet, and the Tb enrichment only existed at the triangular grain boundary.

scholarly journals Coercivity enhancement in heavy rare earth-free NdFeB magnets by grain boundary diffusion process

2018 ◽  
Vol 113 (15) ◽  
pp. 152402 ◽  
Author(s):  
D. Salazar ◽  
A. Martín-Cid ◽  
R. Madugundo ◽  
J. M. Barandiaran ◽  
G. C. Hadjipanayis
Keyword(s):  
Rare Earth ◽  
Grain Boundary ◽  
Diffusion Process ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Heavy Rare Earth ◽  
Ndfeb Magnets

scholarly journals Comparison on the coercivity enhancement of sintered NdFeB magnets by grain boundary diffusion with low-melting (Tb, R)75Cu25 alloys (R= None, Y, La, and Ce)

AIP Advances ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 125238 ◽  
Author(s):  
Y. J. Wong ◽  
H. W. Chang ◽  
Y. I. Lee ◽  
W. C. Chang ◽  
C. H. Chiu ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Ndfeb Magnets

scholarly journals Faceted shell structure in grain boundary diffusion-processed sintered Nd–Fe–B magnets

2014 ◽  
Vol 617 ◽  
pp. 884-892 ◽  
Author(s):  
U.M.R. Seelam ◽  
T. Ohkubo ◽  
T. Abe ◽  
S. Hirosawa ◽  
K. Hono
Keyword(s):  
Grain Boundary ◽  
Shell Structure ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion

scholarly journals Comparison on the coercivity enhancement of the sintered NdFeB magnets by grain boundary diffusion with Tb70Cu30 powders prepared by different milling methods

AIP Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 025101
Author(s):  
Y. J. Wong ◽  
W. C. Hsu ◽  
H. W. Chang ◽  
Y. I. Lee ◽  
W. C. Chang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Ndfeb Magnets

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

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2583
Author(s):  
Pengpeng Qu ◽  
Feifei Li ◽  
Sajjad Ur Rehman ◽  
Lei He ◽  
Xiaoqiang Yu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Grain Boundary ◽  
Diffusion Process ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Shell Structures ◽  
Core Shell ◽  
Thermal Stability Of

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.

Clarifying the effects of La and Ce in the grain boundary diffusion sources on sintered NdFeB magnets

2019 ◽  
Vol 6 (10) ◽  
pp. 106105 ◽  
Author(s):  
H X Zeng ◽  
H Y Yu ◽  
Q Zhou ◽  
J S Zhang ◽  
X F Liao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Ndfeb Magnets
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