Replica Electron Microscopy and X-ray Diffraction Studies on Siliconized Layer Formed on Cast Iron

Abstract

A good heat resistant and non-porous siliconized layer containing 6∼11% Si was obtained on the surface of cast iron with the thickness of 30∼80 μ. The microscopic structure of the siliconized layer was studied by electron microscope and X-ray diffraction method, in comparison with Fe-9% Si alloy. The results are as follows:
(1) Etched patterns were observed in the siliconized layer. The pattern showed the oriented structure like Widmanstätten structure, and vanished through reheating and rapid cooling. The same kind of pattern was observed in Fe-9% Si alloy by cooling slowly from above 900°C or holding below 600°C.
(2) The structure observed both in the siliconized layer and Fe-9% Si alloy was explained in connection with the formation of Fe₃Si superlattice. It is thought that anti-phase domain boundaries of the Fe₃Si superlattice of the DO₃ type was developed by etching.