Phase transformations during the disproportionation stage in the solid HDDR process in a Nd16Fe76B8 alloy

Gutfleisch, Oliver; Martinez, N.; Verdier, M.; Harris, I.R.

doi:10.1016/0925-8388(94)90845-1

Cited by 51 publications

(15 citation statements)

References 9 publications

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“…surrounding them. This observation is in agreement with previous studies [23] which showed that the disproportionation reaction initiates at interfaces such as the grain boundaries and the interface between the Fe dendrites and the matrix. The irregular appearance of the previously smooth α-Fe dendrites was also apparent in previous studies which showed that there was…”

Section: Msupporting

confidence: 94%

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The Hydrogen Ductilisation Process (HyDP) for shaping NdFeB magnets

Brooks

Walton

Zhou

et al. 2017

Journal of Alloys and Compounds

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Section: Msupporting

confidence: 94%

“…(~650 o C or higher). It was also shown that, when the Nd-rich eutectic phase at the grain boundaries is initially in the liquid state, then, when hydrogen is introduced there is a rapid onset of the disproportionation reaction starting at the, now solid, grain boundaries and other interfacial regions [23].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

The Hydrogen Ductilisation Process (HyDP) for shaping NdFeB magnets

Brooks

Walton

Zhou

et al. 2017

Journal of Alloys and Compounds

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“…The Nd 12.5 Fe bal Co 8 B 6.5 (mol%) cast alloy was subjected to annealing at 1110 • C for 16 h in an argon atmosphere, and was mechanically pulverized to obtain starting alloy powder consisting of 53-300 µm particles. In this study, isothermal HDDR [4] (solid HDDR [5]) treatment as displayed in Fig. 1 was applied to the starting alloy powder.…”

Section: Methodsmentioning

confidence: 99%

Relationship between Coercivity and Microstructural Changes During DR Treatment in the HDDR‐processed NdFeCoB Alloy

Nishiuchi

Hirosawa

Nakamura

et al. 2008

IEEJ Transactions Elec Engng

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Relationship between coercivity and microstructural changes during desorption‐recombination (DR) treatment in the hydrogenation‐decomposition‐desorption‐recombination (HDDR) processed NdFeCoB alloy has been studied by a combination of different experimental methods. In the early DR stage, coercivity was very small and after a certain period of the DR treatment, the coercivity abruptly increased. The corresponding changes in positron lifetime spectrum, X‐ray diffraction (XRD) spectrum, and thermal desorption spectrum (TDS) were measured. The changes suggest that an Nd‐rich phase formed among recombined Nd2(Fe,Co)14B grains in the DR treatment plays an important role for the onset of coercivity in the Nd‐Fe‐Co‐B HDDR‐processed alloy. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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“…Disproportionation starts at the Nd-rich grain boundary, which acts as a diffusion path for the hydrogen, and then proceeds towards the centre of the initial grains [4], [7]. The disproportionated regions (Fig.…”

Section: A Disproportionated Statementioning

confidence: 99%

“…The disproportionation of the Nd2Fe14B phase takes place under H2-atmosphere and at elevated temperatures. Complex diffusion mechanisms [3], [4] lead to an intimate mixture of a-Fe, NdH-2 and Fe2B during the following disproportionation reaction: Nd2Fel4B + 2 h H2 11.) 2 NCUH2; t x + 12 a-Fe + FQB.…”

Section: Introductionmentioning

confidence: 99%

Detailed TEM analysis of solid-HDDR Nd/sub 16/Fe/sub 76/B/sub 8/ magnetic materials

Matzinger

Fidler

Gutfleisch³

et al. 1995

IEEE Trans. Magn.

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Detailed microstructural characterization was carried out by means of transmission electron microscopy on a N d l &~& g alloy during various stages of a S(So1id)-HDDR process (T = 8OO"C, p(H2) = 0.7 bar). The disproportionated, colony-type matrix consists of parallel aligned NdH-2 cylinders of submicron size, embedded in an a-Fe matrix. There is a crystal orientation relationship within each colony:NdH2 (1 0 01 II *Fe (1 0 01, NdH2 CO 0 1s II *Fe CO 0 %>. Grains of FQB with an average size of 100 nm show planar crystal defects and are randomly distributed within the matrix. The recombmation starts with a coarsening process in each colony. In an early recombined NdzFe14B matrix, remaining spherical Nd-rich and aJ?e regions were found. Further vacuum annealing leads to a refined Nd2Fe14B matrix with some remaining @Fe inclusions. Due to Nd diffusion from the grain boundaries into the disproportionated r ions, some Nd-rich material can be found at the triple points 3 the recombined NdzFqfi grains.

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Phase transformations during the disproportionation stage in the solid HDDR process in a Nd16Fe76B8 alloy

Cited by 51 publications

References 9 publications

The Hydrogen Ductilisation Process (HyDP) for shaping NdFeB magnets

The Hydrogen Ductilisation Process (HyDP) for shaping NdFeB magnets

Relationship between Coercivity and Microstructural Changes During DR Treatment in the HDDR‐processed NdFeCoB Alloy

Detailed TEM analysis of solid-HDDR Nd/sub 16/Fe/sub 76/B/sub 8/ magnetic materials

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