Raman imaging in corrosion science: High‐temperature oxidation of the zirconium alloys used in the nuclear industry as an example

Successive technological improvements have made Raman imaging systems very efficient. Raman imaging applications now cover a wide range of scientific fields, including high‐temperature materials corrosion, also known as dry corrosion. The analysis of the phenomena occurring during corrosion requires knowledge in metallurgy, thermodynamics, chemical kinetics, solid‐state chemistry, and physics. Part of this information (crystallographic phases, stress state, oxygen transport, etc.) can be obtained, at least qualitatively, from the analysis of Raman images of the oxidation layer. Throughout this paper, we consider as a prototypal example the oxidation of a particular zirconium alloy, Zircaloy‐4, used in the nuclear industry as cladding materials in light‐water reactors. Through some examples, the aim of the present paper is to describe what kind of information this method can bring, to review its merits and weaknesses. The analysis protocols methods described herein are not exhaustive, but most probably represent a simple way to read and understand the Raman images. These few examples show that rather subtle details that concern phase distribution, strain, and oxygen transport can effectively be captured by this method. Most probably, Raman imaging may be applied to other alloys or systems as well.