Role of Crystal Orientation in the Oxidation of Iron

Abstract

The interface between a metal and its oxide or other corrosion films is a zone of great interest in the general phenomena of protection of metals. The system of iron and its oxides is considered in this work. Experiments are made using the electron diffraction high temperature camera on the oxidation of single crystals of iron. Definite orientation effects are found between the metal and the oxide if the oxidation is carried out slowly, for example, in a 50 per cent ‐50 per cent mixture at 750°C or in high vacuum. Rapid oxidation shows that the original orientation effects are not carried through to thick films.The orientation effects are interpreted in terms of two principles: (a) the conservation of similar repeat distances in the two lattices and (b) conservation of atom density. The effect of the forward and reverse solid phase reaction is studied and it is shown that the orientation effects are carried through to the newly formed oxide. The results are discussed in their relationships to the general phenomena of oxidation and corrosion.