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Al Grain Boundary Embrittlement Promoted by Na Impurity: An ab initio Study

Published online by Cambridge University Press:  21 March 2011

Guang-Hong Lu
Affiliation:
Ryoichi Yamamoto Institute of Industrial Science, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106-8558, Japan
Masanori Kohyama
Affiliation:
Department of Materials Physics, Osaka National Research Institute, AIST, 1-8-31 Midorigaoka, Ikedashi, Osaka 563-8577, Japan
Rayoichi Yamamoto
Affiliation:
Ryoichi Yamamoto Institute of Industrial Science, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106-8558, Japan
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Abstract

We calculate the electronic structure of AlΣ9 tilt grain boundary with substitutional Na impurity atoms by first principles pseudopotential method. Results show that by Na segregation Al grain boundary expands and the valence charge density decreases significantly along the boundary. There is no stronger bond than metallic bond in the boundary even with Na impurity. We therefore conclude that the mechanism of Na-promoted Al grain boundary embrittlement should be one kind of ‘decohesion model’.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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