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Heat treatment of Metastable Nd<sub>2</sub>Fe<sub>17</sub>B<sub>x</sub> Phase Formed from Undercooled Melt of Nd-Fe-B Alloys

Ozawa, S. and Kuribayashi, K. and Hirosawa, S. and Reutzel, S. and Herlach, D. M. (2006) Heat treatment of Metastable Nd<sub>2</sub>Fe<sub>17</sub>B<sub>x</sub> Phase Formed from Undercooled Melt of Nd-Fe-B Alloys. Journal of Applied Physics, 100 (12), 123906-1-123906-8. American Institute of Physics. DOI: 10.1063/1.2386943.

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Abstract

Alloys of Nd<sub>10</sub>Fe<sub>85</sub>B<sub>5</sub>, Nd<sub>12</sub>Fe<sub>82</sub>B<sub>6</sub>, and Nd<sub>14</sub>Fe<sub>79</sub>B<sub>7</sub> were melted and then solidified under the containerless state using a drop tube. In the as-dropped sample, a large amount of the Nd<sub>2</sub>Fe<sub>17</sub>B<sub>x</sub> was contained as a metastable phase. Particularly in relatively large samples, the metastable phase, which was partially decomposed into the Nd<sub>2</sub>Fe<sub>14</sub>B and <font face="symbol">a</font>-Fe phases, shows a microstructure similar to that of normalized low-carbon steel. The heat treatment of the as-dropped samples induces a dual- stage phase transformation. The 1st stage of the phase transformation, which is dominant in the Nd<sub>14</sub>Fe<sub>79</sub>B<sub>7</sub> alloy, is the diffusive phase transformation from Nd<sub>2</sub>Fe<sub>17</sub>B<sub>x</sub> and Nd-rich phases into the Nd<sub>2</sub>Fe<sub>14</sub>B phase at 950 K, and the 2nd stage of the transformation, which is dominant in the Nd<sub>10</sub>Fe<sub>85</sub>B<sub>5</sub> alloy, is the decomposition of the metastable phase into the Nd<sub>2</sub>Fe<sub>14</sub>B and <font face="symbol">a</font>-Fe phases at 1100 K. Although the rate of the phase transformation in either stage is controlled by the diffusion of Nd atoms, the diffusivity at the 1st stage of the phase transformation, being large due to the existence of the Nd-rich phase adjacent to the Nd<sub>2</sub>Fe<sub>17</sub>B<sub>x</sub> phase, results in a decrease in transformation temperature.

Document Type:Article
Title:Heat treatment of Metastable Nd<sub>2</sub>Fe<sub>17</sub>B<sub>x</sub> Phase Formed from Undercooled Melt of Nd-Fe-B Alloys
Authors:
AuthorsInstitution or Email of Authors
Ozawa, S.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan
Kuribayashi, K.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan
Hirosawa, S.Research and Development Center, NEOMAX Co., Ltd., Japan
Reutzel, S.Ruhr-Universität Bochum
Herlach, D. M.UNSPECIFIED
Date:2006
Journal or Publication Title:Journal of Applied Physics
Volume:100
DOI:10.1063/1.2386943
Page Range:123906-1-123906-8
Publisher:American Institute of Physics
Status:Published
Keywords:Unterkühlung von Materialien
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W FR - Forschung unter Weltraumbedingungen (old)
DLR - Research area:Space
DLR - Program:W FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):W - Vorhaben Materialforschung unter Mikro-g (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space > Institute of Space Simulation > Center for Solidification of Undercooled Melts (ZEUS)
Deposited By: Dr.rer.nat. Sven Reutzel
Deposited On:06 Aug 2007
Last Modified:12 Dec 2013 20:21

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