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High-coercivity ultrafine-grained anisotropic Nd–Fe–B magnets processed by hot deformation andthe Nd–Cu grain boundary diffusion process

2013年8月19日(月)

Acta Materialia 61 (2013), pp. 6622-6634 ( DOI information: 10.1016/j.actamat.2013.07.049 )
H. Sepehri-Amin ( NIMS, JST-CREST )
T. Ohkubo ( NIMS, JST-CREST )
S. Nagashima ( Toyota Motor Corporation, Advanced Material Engineering Div. )
M. Yano ( Toyota Motor Corporation, Advanced Material Engineering Div. )
T. Shoji ( Toyota Motor Corporation, Advanced Material Engineering Div. )
A. Kato ( Toyota Motor Corporation, Advanced Material Engineering Div. )
T. Schrefl ( St. Pölten University of Applied Science )
K. Hono ( NIMS, JST-CREST )

Acta Materialia 61 (2013), pp. 6622-6634
DOI information: 10.1016/j.actamat.2013.07.049

Abstract

The grain boundary diffusion process using an Nd70Cu30 eutectic alloy has been applied to hot-deformed anisotropic Nd–Fe–B magnets, resulting in a substantial enhancement of coercivity, from1.5 T to 2.3 T, at the expense of remanence. Scanning electron microscopy showed that the arealfraction of an Nd-rich intergranular phase increased from 10% to 37%. The intergranular phase of thehot-deformed magnet initially contained ∼55 at.% ferromagnetic element, while it diminished to anundetectable level after the process. Microscale eutectic solidification of Nd/NdCu as well as a finelamellae structure of Nd70(Co,Cu)30/Nd were observed in the intergranular phase. Micromagneticsimulations indicated that the reduction of the magnetization in the intergranular phases leads to theenhancement of coercivity in agreement with the experimental observation.


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元素戦略拠点

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触媒・電池元素戦略研究拠点 (京都大学)
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東工大元素戦略拠点 (東京工業大学)
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構造材料元素戦略研究拠点 (京都大学)
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