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The role of Cu addition in the coercivity enhancement of sintered Nd-Fe-B permanent magnets

Published online by Cambridge University Press:  31 January 2011

W.F. Li ,
T. Ohkubo ,
T. Akiya ,
H. Kato  and
K. Hono
T. Ohkubo
Affiliation:
National Institute for Materials Science, Tsukuba 305-0047, Japan
T. Akiya
Affiliation:
New Industry Creation Hatchery Center, Tohoku University, Sendai, Miyagi 980-8579, Japan
H. Kato
Affiliation:
New Industry Creation Hatchery Center, Tohoku University, Sendai, Miyagi 980-8579, Japan; and Department of Applied Mathematics and Physics, Yamagata University, Yamagata 990-8560, Japan
K. Hono
Affiliation:
National Institute for Materials Science, Tsukuba 305-0047, Japan
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Abstract

To understand the mechanism of the coercivity enhancement by a trace addition of Cu in Nd-Fe-B sintered magnets, we investigated the microstructure difference between Cu-doped and Cu-free alloys using high resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), and laser assisted three dimensional atom probe (LA-3DAP). From a serial sectioning back scattered electron (BSE) images of the Nd-rich phase obtained by an integration of the focused ion beam (FIB) and HRSEM technique, it was found that Cu addition leads to a continuous formation of Nd-rich thin layers along the grain boundaries. 3DAP analysis has shown that a thin Cu-rich layer with a thickness of approximately 2 nm is present at the interface between the Nd2Fe14B and Nd-rich phase grains.

Keywords

Grain boundariesMagnetic propertiesMicrostructure
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 2 , February 2009 , pp. 413 - 420
Copyright
Copyright © Materials Research Society 2009

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