The Morphological Stability of Boundaries During Metal Oxidation

1 The Morphological Stability of Boundaries During Metal Oxidation 

Although Chapter 11 is especially devoted to the morphological stability of solid-solid interfaces during reaction, it is necessary in the context of alloy oxidation to 

B10 (A.B)203 IA.B102 j Ojl g) tion paths involving (A,B) alloy and oxide solid solutions, b) Reaction 

Let us try to quantify these ideas by formulating the flux equations for the (semiconducting) oxide (A, B)0 , namely (see Eqn. (6.25)) 

Systematically speaking, so-called internal oxidation reactions of alloys (A,B) are extreme cases of morphological instabilities in oxidation. Internal oxidation occurs if oxygen dissolves in the alloy crystal and the (diffusional) transport of atomic oxygen from the gas/crystal surface into the interior of the alloy is faster than the countertransport of the base metal component (B) from the interior towards the surface. In this case, the oxidation product BO does not form a stable oxide layer on the alloy surface. Rather, BO is internally precipitated in the form of small oxide particles. The internal reaction front moves parabolically ( Vo into the alloy. Examples of internal reactions are discussed quantitatively in Chapter 9. 

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