Multi-phase EBSD mapping and local texture analysis in NdFeB sintered magnets

Woodcock, T.G.; Gutfleisch, Oliver

doi:10.1016/j.actamat.2010.10.033

Cited by 70 publications

(20 citation statements)

References 32 publications

(41 reference statements)

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“…4, many misaligned Nd 2 Fe 14 B grains are in contact with the Nd 2 O 3 grains. The Nd 2 O 3 grains are randomly oriented according to synchrotron radiation and EBSD studies as reported by Woodcock et al [21,42]. In this work, no clear orientation relationship was found between the misaligned Nd 2 Fe 14 B grains and the Nd 2 O 3 grains.…”

Section: Discussionmentioning

confidence: 68%

Structure and chemical compositions of the grain boundary phase in Nd-Fe-B sintered magnets

2016

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a b s t r a c tWe revisited the microstructure of a commercial Nd-Fe-B sintered magnet using scanning electron microscopy (SEM) and aberration corrected scanning transmission electron microscopy (STEM) in order to clarify the microstructure feature that is relevant to the coercivity. Two types of thin Nd-rich grain boundary (GB) phases were found: one is crystalline and the other is amorphous. The crystalline Nd-rich GB phase form at the flat surface of c-plane of the Nd 2 Fe 14 B grains, which contains a higher amount of Nd compared to the amorphous GB phase that form on the grain boundaries nearly perpendicular to the cplanes. This indicates that the intergranular exchange coupling in sintered Nd-Fe-B magnets is anisotropic. Correlative SEM and STEM analysis of triple junction Nd-rich phases revealed five types of Nd-rich phases, i.e., fcc-NdO, hcp-Nd 2 O 3 , NdFe 4 B 4 , metallic Nd-rich phases with the fcc structure and the Ia3 structure. The metallic Nd-rich phases form at the sharp edges of Nd-rich oxide and boride grains, from which thin Nd-rich phases is infiltrated along grain boundaries to form the thin GB phase. Misaligned Nd 2 Fe 14 B grains are often observed in direct contact with the Nd 2 O 3 grains.

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Section: Discussionmentioning

confidence: 68%

Structure and chemical compositions of the grain boundary phase in Nd-Fe-B sintered magnets

2016

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“…Therefore, the structural and chemical modification of the GB in the hot-deformed magnets may lead to a further increase in coercivity. Much effort has recently been made to correlate the GB structure/ chemistry with the coercivity of sintered [11][12][13], hotdeformed [14][15][16] and hydrogenation-disproportionationdesorption-recombination (HDDR) processed Nd-Fe-B magnets [17,18]. A thin GB phase enriched with Nd is already known to exist in all these magnets.…”

Section: Introductionmentioning

confidence: 99%

“…High magnification cross-sectional BSE SEM images of (d) 12.7Nd, (e)13.0Nd and (f) 14.0Nd. c-axis is in-plane as the arrow indicates.…”

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confidence: 97%

Effect of Nd content on the microstructure and coercivity of hot-deformed Nd–Fe–B permanent magnets

et al. 2013

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“…Hence, in this work, we focus on identifying microstructure features of the Dy-rich shells. For characterization of the orientation of the interfaces between the Dy-rich shells and surrounding Nd 2 Fe 14 B grains, we employed electron backscatter diffraction (EBSD) technique, which was first employed to the texture analysis of Nd-Fe-B sintered magnets by Khlopkov et al [19] and more recently by Woodcock and Gutfleisch [20]. In the present work, we have found faced core/shell structure in the GBDP sintered magnets and the faceting planes were identified by EBSD.…”

Section: Introductionmentioning

confidence: 99%

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

Seelam

Ohkubo

Abe

et al. 2014

Journal of Alloys and Compounds

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a b s t r a c tDysprosium enriched shell structure formed by the grain boundary diffusion process (GBDP) of a sintered Nd-Fe-B magnet was characterized by using scanning electron microscopy, electron back-scattered diffraction and transmission electron microscopy. Faceted core-shell interfaces with an abrupt change in Dy concentration suggest the Dy-rich shells are formed by the solidification of the liquid phase during cooling from the GBDP temperature. The Nd-rich phases are almost free from Dy, and their quantity near the surface of a bulk sample is much higher than that in the center, indicating that a higher fraction of a liquid phase exists near the surface during processing at 900°C. These microstructural features are explained on the basis of the phase equilibrium between Nd and Nd 2 Fe 14 B at the processing temperature and subsequent cooling. Based on the results, we discuss the coercivity enhancement by the GBDP using Dy vapor.

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Multi-phase EBSD mapping and local texture analysis in NdFeB sintered magnets

Cited by 70 publications

References 32 publications

Structure and chemical compositions of the grain boundary phase in Nd-Fe-B sintered magnets

Structure and chemical compositions of the grain boundary phase in Nd-Fe-B sintered magnets

Effect of Nd content on the microstructure and coercivity of hot-deformed Nd–Fe–B permanent magnets

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

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