Effects of alignment on the magnetic and mechanical properties of sintered Nd–Fe–B magnets

Cui, Xiquan; Cui, C.Y.; Cheng, Xiao Nong; Xu, Xiaojing; Ma, Tianyu; Yan, Mi; Wang, C.

doi:10.1016/j.jallcom.2013.02.093

Cited by 29 publications

(4 citation statements)

References 12 publications

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“…Driven by the principle that the Nd-rich GB phase is critical to the corrosion resistance, coercivity, heavy RE utilization, as well as the high-abundant RE application in Nd-Fe-B magnets, we have devoted intense efforts in modifying the grain boundary. [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] The dual-alloy method invented in the 1990s inspired us the possibility of designing a novel GB alloy to replace the traditional Nd-rich phase. A novel approach, named as grain boundary restructuring (GBR), was proposed accordingly.…”

Section: What Is Grain Boundary Restructuringmentioning

confidence: 99%

Grain boundary restructuring and La/Ce/Y application in Nd–Fe–B magnets*

Yan

Jin

2019

Chinese Phys. B

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Since the 1980s, Nd–Fe–B with largest energy product (BH)max approaching the theoretical limit has become the landmark of permanent magnetic material. The application spectrum for Nd–Fe–B continues to expand over time both in the industrial and commercial sectors, which leads to growing research interests for solving the long-standing drawbacks of Nd–Fe–B, i.e., poor corrosion resistance, low coercivity, high Dy/Tb and low La/Ce/Y consumption. Concerning the above obstacles, we aim to present the novel grain boundary restructuring (GBR) approach, from GB design, processing, to structure evolution and property evaluation with a focus on the corrosion and coercivity mechanism of the restructured 2:14:1-typed magnets. Starting with an introduction to the fundamental of GBR, two representative examples, high-electrode-potential (Pr, Nd)32.5Fe62.0Cu5.5 and low-melting-point Dy71.5Fe28.5, are given with detailed descriptions of the advantages of GBR to enhance the intrinsic anti-corrosion stability and to strengthen the coercivity at low Dy consumption. Microstructure–property correlations are established to understand the critical importance of regulating the restructured GB phase to maximize the all-round performance of the 2:14:1-typed permanent magnets. Aiming at sustainable and balanced development of rare earth (RE) industry, the proceeding section proposes new prototypes of La–Ce and Y–Ce co-substitutions with dual benefits of stabilizing the 2:14:1 tetragonal phase and strengthening the intrinsic hard magnetism. The findings of additional REFe2 intergranular phase delight that the GBR approach also opens up a new horizon of research and application to develop high-performance La/Ce/Y-rich permanent magnets with deliberately tailored GB phase.

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Section: What Is Grain Boundary Restructuringmentioning

confidence: 99%

Grain boundary restructuring and La/Ce/Y application in Nd–Fe–B magnets*

Yan

Jin

2019

Chinese Phys. B

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“…In Nd-Fe-B sintered magnets, the amount of weak Nd-rich phase distributes on the plane perpendicular to the c axis with increasing the alignment, so that the cleaving propagation is easier to occur [32].…”

Section: Resultsmentioning

confidence: 99%

Effect of grain alignment distribution on magnetic properties in (MM, Nd)–Fe–B sintered magnets

Yue

Zhu

et al. 2018

J. Phys. D: Appl. Phys.

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H cj of (MM x Nd 1−x )-Fe-B sintered magnets decreases distinctly with x increasing when misch metal (MM) content (x) ranges from 0.3 to 1. Practical application is taken into consideration so that the (MM 0.6 Nd 0.4 )-Fe-B components are chosen to analyze the changes in behavior of the magnetic properties. Both Magnet II and Magnet III belong to (MM 0.6 Nd 0.4 )-Fe-B sintered magnets, however, it should be noted that Magnet II is prepared by the single alloying method (SAM) and Magnet III is prepared by the double main phase alloy method (DMPAM). Core-shell structures of the magnets prepared by DMPAM can result in the higher H cj and lower knee-point coercivity (H k ) compared with that by SAM. Furthermore, for Magnet II, the abnormal grain growth contributes to a better grain alignment and smaller distribution coefficient (σ) defined as the degree of grain alignment, which will enforce a higher tendency of the H cj decreasing and H k increasing. The expression of their normalized coercivity h(σ) is deduced by combining Gao's starting field model with Kronmüller's nucleation mechanism. Based on the overall h(σ) ~ σ curve, the best desirable h(σ) value is calculated when σ = 0.09. Theoretically, for Magnet III, the resultant larger σ should be attributed to the more uniform grain alignment. In addition, the deviations of grain size distributions on the c-plane become more remarkable with more MM concentrates, which can be presented by SEM images. Meanwhile, by means of the pole figures, it is also verified that the grain alignment distribution becomes much more diverse with x increasing. Therefore, it can be predicted whether the grain alignment distribution is significant for H k and H cj of (MM x Nd 1−x )-Fe-B sintered magnets (x ≠ 0.6) prepared by SAM/DMPAM or not.

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“…7). The weak Nd-rich phase distributed along the grain boundaries is the main reason for the intergranular fracture of the magnet [4]. This indicates that although the metallic coating greatly improves the impact toughness, it cannot change the intrinsic fracture mechanism of sintered NdFeB magnet.…”

Section: Impact Toughness and Fractography Analysismentioning

confidence: 99%

“…Sintered NdFeB magnet possesses superior magnetic properties and has attracted significant attention in recent years [1][2][3]. However, it tends to undergo the intergranular brittle fracture under the load due to the strong uniaxial magnetocrystalline anisotropy, few slip system and weak Nd-rich grain boundary phase [4]. Therefore, its toughness is very poor, seriously limiting its further application in the numerous load-bearing fields.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the Impact Toughness of Sintered NdFeB Magnets via Surface Coating

Cui¹,

Pan²,

Cui³

et al. 2018

JMAG

Self Cite

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Metallic coating by electroplating is commonly attractive for improving the corrosion resistance of sintered NdFeB magnets. However, its tailoring of mechanical characteristics for sintered NdFeB magnets has been seldom concerned. Herein, the impact toughnesses of sintered NdFeB magnets with various metallic coatings (Ni or Ni/Sn) were comparatively investigated. The results indicate that the impact toughnesses of sintered NdFeB magnets are both improved by Ni coating and Ni/Sn bilayer coating. And Ni/Sn bilayer coating exhibits more enhancement of the impact toughness, increased by 41.6 % compared with the original magnet. Moreover, the microstructural observations of the metallic coatings and the fracture were conducted, and the enhanced mechanism of impact toughness for the magnet is analyzed. These findings may provide a reference for toughening the brittle materials.

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Effects of alignment on the magnetic and mechanical properties of sintered Nd–Fe–B magnets

Cited by 29 publications

References 12 publications

Grain boundary restructuring and La/Ce/Y application in Nd–Fe–B magnets*

Grain boundary restructuring and La/Ce/Y application in Nd–Fe–B magnets*

Effect of grain alignment distribution on magnetic properties in (MM, Nd)–Fe–B sintered magnets

Tailoring the Impact Toughness of Sintered NdFeB Magnets via Surface Coating

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