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Metastable solidification of NdFeB alloys by drop-tube processing

Published online by Cambridge University Press:  31 January 2011

Jianrong Gao ,
Th. Volkmann  and
D. M. Herlach
Jianrong Gao*
Affiliation:
Institute of Space Simulation, DLR, D-51170 Cologne, Germany Department of Applied Physics, Northwestern Polytechnical University, Xian 710072, China
Th. Volkmann
Affiliation:
Institute of Space Simulation, DLR, D-51170 Cologne, Germany Institute of Experimental Physics, Ruhr University of Bochum, D-44780 Bochum, Germany
D. M. Herlach
Affiliation:
Institute of Space Simulation, DLR, D-51170 Cologne, Germany
*
a)Author all correspondence to this author.
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Abstract

Metastable solidification of small droplets of Nd11.8Fe82.3B5.9 and Nd14Fe79B7 alloys was performed in an 8-m drop tube filled with helium. The results showed that the solidification path of the droplets depends on the alloy composition and on the droplet size. For Nd11.8Fe82.3B5.9 alloy, larger droplets are solidified by primary iron formation and subsequent Nd2Fe14B crystallization from the residual liquid phase, whereas smaller ones tend to be frozen by metastable primary Nd2Fe17Bx growth (x = 0–1). A similar transition of the solidification path from primary iron formation to primary Nd2Fe17Bx formation occurred in Nd14Fe79B7 alloy with reducing droplet size. However, metastable primary growth of Nd2Fe14B was also observed within a wide droplet size range prior to the appearance of the metastable Nd2Fe17Bx phase. Nucleation and growth of different phases were considered to produce an explanation of the observed phase selection phenomena in these two alloys.

Type
Articles
Information
Journal of Materials Research , Volume 16 , Issue 9 , September 2001 , pp. 2562 - 2567
Copyright
Copyright © Materials Research Society 2001

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