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First-principles pseudopotential study of an aluminium grain boundary containing sulphur atoms |
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| Authors: | Guang-Hong Lu Masanori Kohyama Ryoichi Yamamoto |
| Affiliation: | 1. Institute of Industrial Science , University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan;2. School of Science , Beijing University of Aeronautics and Astronautics , 37 Xueyuan Road, Haidian District, Beijing, 100083, PR China;3. Special Division of Green Life Technology , National Institute of Advanced Industrial Science and Technology , 1-8-31 Midorigaoka, Ikedashi, Osaka, 563-8577, Japan;4. Institute of Industrial Science , University of Tokyo , 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan |
| Abstract: | The electronic structure of an aluminium grain boundary with segregated sulphur impurity atoms has been calculated by a first-principles pseudo-potential method. It is found that a sulphur atom bonds to only one of the neighbouring aluminium atoms. This bond is a mixed-character metallic-covalent bond which is stronger than the metallic Al-Al bonds. Electrons that participate in forming this bond are 3p electrons of sulphur but not its 3s electrons. Other Al--S bonds in the boundary contain no covalent character. From the nature of Al--S bonds in the boundary it cannot be decided whether the embrittlement promotion mechanism by sulphur segregation should be classified as a 'bond mobility model' or a 'decohesion model'. |
| Keywords: | grain boundary sliding first principles calculation alumina |