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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.43  No.11 (2002)  >  pp.2673-2677

MATERIALS TRANSACTIONS
<<Previous article Vol.43  No.11 (2002)   pp.2673 - 2677 Next article>>

Microstructural Improvement of NdFeB Magnetic Powders by the Zn Vapor Sorption Treatment

L. Y. Zhu1), T. Hirae1), M. Itakura1), N. Kuwano2) and K. Machida3)
1) Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences,Kyushu University
2) Advanced Science and Technology Center for Cooperative Research, Kyushu University
3) Collaborative Research Center for Advanced Science and Technology, Osaka University


The microstructural modification for NdFeB magnetic powders (MQP-B) after Zn vapor sorption has been investigated by transmission electron microscopy (TEM). It is found that a coating layer about 100 nm thick was formed on the surface of powder. Selected area electron diffraction (SAED) pattern and high resolution transmission electron microscopy (HRTEM) analyses show that the coating layer consists of condensed nano-scale crystallites of Fe11Zn40, NdZn5 and Zn. After the temperature for Zn vapor sorption is raised to 648 K, a thin layer has been formed on boundaries of Nd2Fe14B grains locally in the rim region of the powders. The morphology of the grain-boundary thin-layers is very similar to that in HDDR-NdFeB magnet powder after Zn vapor sorption treatment. Since the latter has a good thermal stability of magnetic property, the Zn vapor sorption treatment is expected to improve also the thermal stability of MQP-B magnet.


Keyword:
NdFeB alloy, magnetic powder, Zinc coating, microstructure, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM)

Received: June 20, 2002
Accepted: August 07, 2002 , Published online: September 06, 2005
Copyright (c) 2005 The Japan Institute of Metals

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