Internal oxidation

Internal oxidation, in corrosion of metals, is the process of formation of corrosion products (e.g. a metal oxide) within the metal bulk. In other words, the corrosion products are created away from the metal surface, and they are isolated from the surface.[1]

Internal oxidation occurs when some components of the alloy are oxidized in preference to the balance of the bulk.^[clarification needed] The oxidizer is often oxygen diffusing through the metal bulk from the interface, but it can be also another element (for example sulfur or nitrogen).

Internal oxidation is a well-known corrosion mechanism of nickel-based alloys in the temperature range of 500 to 1200 °C.[2]

Internal oxidation is distinct from selective leaching.

References

1. "ASM Handbook Vol.13 Corrosion", ASM International, 1987, page 8.
2. P. M. Scott, "AN OVERVIEW OF INTERNAL OXIDATION AS A POSSIBLE EXPLANATION OF INTERGRANULAR STRESS CORROSION CRACKING OF ALLOY 600 IN PWRS", Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, The Minerals, Metals & Materials Society (TMS), 1999. (pdf)