Simultaneous application of Dy–X (X= F or H) powder doping and dip-coating processes to Nd–Fe–B sintered magnets

Kim, Tae Hoon; Lee, Seong Rae; Kim, Hyo Jun; Lee, Min Woo; Jang, Tae Suk

doi:10.1016/j.actamat.2015.04.019

Cited by 93 publications

(17 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A remarkable large grain-sized structure with residual nano-scale and sub-micron grains is observed in both annealed magnets. Most of large grains with a rectangular shape suggest that the new structure, derived from the platelet-shaped nano-structure, is significantly different from the sintered magnets789. In annealed die-upset magnets, a series of nano-scale Nd-rich aggregations are found inside large Nd 2 Fe 14 B grains, and the distance of neighboring aggregations is about 24 μm, similar to the thickness of deformed melt-spun ribbons.…”

Section: Resultsmentioning

confidence: 93%

“…The limited natural abundance and the rapidly increasing cost of HRE elements have led to the need for an urgent development of less HRE-containing magnets with high H c . To decrease the usage of HRE and minimize the M r loss, the grain boundary diffusion process (GBDP) using HRE and HRE compounds is widely studied to prepare high-coercivity sintered magnets789101112. The die-upset magnets with an ultrafine-grained structure are believed to be a potential to obtain higher H c .…”

mentioning

confidence: 99%

See 1 more Smart Citation

Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

Wang

et al. 2016

Sci Rep

View full text Add to dashboard Cite

Ultrafine-grained die-upset Nd-Fe-B magnets are of importance because they provide a wide researching space to redesign the textured structures. Here is presented a route to obtain a new die-upset magnet with substantially improved magnetic properties. After experiencing the optimized heat treatment, both the coercivity and remanent magnetization of the Dy-Cu press injected magnets increased substantially in comparison with those of the annealed reference magnets, which is distinct from the reported experimental results on heavy rare-earth diffusion. To study the mechanism, we analyzed the texture evolution in high-temperature annealed die-upset magnets, which had significant impact on the improvement of remanent magnetization. On basis of the results, we find that the new structures are strongly interlinked with the initial structures. With injecting Dy-Cu eutectic alloy, an optimized initial microstructure was achieved in the near-surface diffused regions, which made preparations for the subsequent texture improvement. Besides, the Dy gradient distribution of near-surface regions of the Dy-Cu press injected magnets was also investigated. By controlling the initial microstructure and subsequent diffusion process, a higher performance magnet is expected to be obtained.

show abstract

Section: Resultsmentioning

confidence: 93%

mentioning

confidence: 99%

Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

Wang

et al. 2016

Sci Rep

View full text Add to dashboard Cite

show abstract

“…In addition, Fhas positive effects on saving the HRE resources. For instance, since a reaction of Nd 2 O 3 + 2DyF 3 → (Nd,Dy) 4 O 3 F 6 occurs during GBD, Dy is suppressed to be consumed at a stable (Nd,Dy) 2 O 3 phase [41,42]. The chemical potential for Dy diffusion can be increased by F − anions in Nd 2 Fe 14 B grain, and thus the Dy atoms in the (Nd,Dy) 4 O 3 F 6 phase can diffuse into the 2:14:1 lattice [43,44].…”

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

View full text Add to dashboard Cite

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.

show abstract

“…The post-sintering annealing heat treatment permit the HRE elements diffuse into the magnets along the grain boundaries and then into the outer region of the Nd2Fe14B grains, resulting in a core-shell microstructure [2,4,7]. The changes in the core-shell microstructure and the grain boundary diffusion depth of HRE elements also affect the coercivity of the magnet [10][11]. The existence of a core-shell microstructure was strongly related to the drastically improved coercivity [10].…”

Section: Introductionmentioning

confidence: 96%

“…Heat treatment is known to be an effective way to improve the magnetic properties by changing the microstructure of grain boundary [13]. During heat treatment, the Nd-Fe-B magnets were annealed at 900°C to permit grain boundary diffusion of Dy, then annealed at 500°C for modification of the microstructure of Nd-rich phases [11].…”

Section: Introductionmentioning

confidence: 99%

Effect of DyF3 and TbF3 additions on the coercivity enhancement in grain boundary diffusion processed Nd-Fe-B permanent magnets

Pratomo¹,

Oktadinata²,

Pawawoi³

2018

AIP Conference Proceedings

View full text Add to dashboard Cite

Simultaneous application of Dy–X (X= F or H) powder doping and dip-coating processes to Nd–Fe–B sintered magnets

Cited by 93 publications

References 20 publications

Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

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

Effect of DyF3 and TbF3 additions on the coercivity enhancement in grain boundary diffusion processed Nd-Fe-B permanent magnets

Contact Info

Product

Resources

About