利用EBSD鑑定鋁化低碳鋼中Fe-Al與Fe-Al-Si介金屬相之晶體結構

EBSD Study of Crystallographic Identification of Fe-Al and Fe-Al-Si Intermetallic Phases in Aluminide Coatings on Mild Steels

鄭維仁(W. J. Cheng) ； 王朝正(C. J. Wang)

《防蝕工程》 24卷2期 (2010/06) Pp. 71-76

https://doi.org/10.6376/JCCE.201006.0071

摘要

本研究採用低碳鋼熱浸於700℃之純鋁與鋁-10 wt.%矽熔湯中180秒。藉由掃瞄式電子顯微鏡(scanning electron microscope, SEM)、能量分散光譜儀(energy dispersive X-ray spectroscopy, EDS)、X-ray繞射儀(X-ray diffraction, XRD)與電子背向散射繞射(electron backscatter diffraction, EBSD)技術，鑑定熱浸鋁化層中Fe-Al或Fe-Al-Si介金屬相之晶體結構。研究結果顯示，熱浸純鋁相較於熱浸鋁矽之鋁化層具有較厚之介金屬層，並且由少量的單斜晶FeAl3與主要的斜方晶Fe2Al5所組成。另一方面，相較於熱浸純鋁，熱浸鋁矽其介金屬層除了可以發現與熱浸純鋁相同之FeAl3與Fe2Al5相外，也具有六方晶Al7Fe2Si與三斜晶(Al, Si)5Fe3之Fe-Al-Si介金屬化合物。因此，可以推判添加矽元素於鋁湯中將改變鋁化層中介金屬相之晶體結構。

關鍵字

低碳鋼 ； 熱浸 ； 相鑑定 ； 鋁化層 ； 電子背向散射繞射

並列摘要

Mild steels were coated by hot-dipping in molten aluminum and aluminum-silicon baths at 700℃ for 180 s, respectively. Phase identification on the Fe-Al and Fe-Al-Si intermetallic phases in the hot-dipped aluminide steels was carried out by combined analyses of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The results showed that the aluminide layer of the steel dipped in Al melt possessed a thicker intermetallic layer than that of the steel dipped in Al-Si melt, and this intermetallic layer was composed of minor monoclinic FeAl3 and major orthorhombic Fe2Al5. On the other hand, the intermetallic layer of the steel hot-dipped in Al-Si melt was composed of not only the same FeAl3 and Fe2Al5 phases but also the Fe-Al-Si intermetallic phases of hexagonal Al7Fe2Si and triclinic (Al, Si)5Fe3, implying that the addition of the silicon in the aluminum bath altered the crystal structure of the intermetallic phase in the aluminide layer.

並列關鍵字

Mild steel ； Hot-dipping ； Phase identification ； Aluminide layer ； EBSD