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 ~ 50 per cent H~O-50 per cent H2 mixture at 750~ 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 Fe304 + Fe --~ 4FeO 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.

Effects of interfacial interactions between metal and process control agents during ball milling on the microstructure of the milled Fe-based nanocrystalline alloy powder

“…The average grain size (∼20 nm) well agreed with the period of the granular pattern in the lateral force images of the milled alloys exposed to the atmosphere [ Figure 1 (b-3) and (b-4)]. The growth rate of the oxide layer was determined from the crystal plane of the iron surface due to the lattice matching between Fe and oxides ( Gulbransen and Ruka, 1952 ). The formation rates of oxide follow the order (100) > (111) > (110) ( Boggs et al., 1967 ).…”

Oriented Dioxide Films on Uranium

“…This occurrence appears to be unusual since it is commonly thought that the first layers of oxide are oriented epitaxially with the parent metal. For example, Gulbransen and Ruka (1), employing electron diffraction, showed that strongly oriented films are obtained on iron in H.~ + H~O mixtures and that these bear a rational epitaxial relationship to underlying metal. Mehl and McCandless (2) oxidized single crystals of iron in wet hydrogen and obtained the same epitaxial relations by x-ray diffraction on films thick enough to show interference colors.…”

Adhesion Using Molecular Models. Adhesion of Polyethylene and Poly(vinyl Chloride) to Metals

“…Titanium and iron were selected for study because of the practical importance of these metals as adherends. The basis for the selection of the oxides was: Ti-O appears to be the oxide most likely to form on the surface of titanium (5,20); Fe2Os is very close in structure to Cr2Os, which seems to be the predominant oxide in the surface of stainless steel (1, 5, 24); -FeO is believed to be the most probable oxide in the surface of pure iron, as it undergoes transition to Fe2Os (4,11). After preparation, all the ions of each surface model were checked for accuracy of size and spacing.…”