MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
In-situ Observation of Growth Behavior of Fe-Zn Intermetallic Compounds at Initial Stage of Galvannealing Process
Akira TaniyamaMasahiro AraiToru TakayamaMasugu Sato
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2004 Volume 45 Issue 7 Pages 2326-2331

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Abstract

In-situ observation was performed with X-ray diffraction technique using synchrotron radiation to reveal growth behavior of the Fe-Zn intermetallic compounds, the ζ and δ1 phases, at the initial stage of galvannealing process. The galvanized sample and electroplated sample were used in the observation. The diffraction peak profiles were successfully obtained at intervals of 1 second with heating the sample, and the growth of the Fe-Zn intermetallic compounds was observed dynamically. In the galvanized sample including a small amount of aluminum in the coating, there was an incubation period of 7 seconds before the δ1 phase started to grow. The thickness estimated with the peak intensity of the δ1 phase increased in proportion to the square root of heating time when the incubation period was taken into account. In the electroplated sample including no aluminum in the coating, the thickness of ζ phase increased in proportion to the square root of heating time. The δ1 phase started to grow as soon as the ζ phase occupied the entire coating. The thickness of the δ1 phase also increased in proportion to the square root of heating time. These results suggest that that the growth behavior of the δ1 phase at the initial stage of galvannealing is dominated by the interdiffusion between Fe and Zn, neither by interfacial reaction nor by autocatalytic reaction whether the coating contains aluminum or not.

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© 2004 The Japan Institute of Metals and Materials
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