The Nanostructure of the Oxide Formed on Fe-10Cr-4Al Exposed in Liquid Pb

An Fe-10Cr-4Al alloy containing reactive elements developed for application in high-temperature liquid lead environments was analyzed after exposure in 600 and 750 degrees C lead with dissolved oxygen for 1,000-2,000 h. Atom probe tomography, transmission electron microscopy, and X-ray scattering were all used to study the protective oxide formed on the surface. Exposure at 750 degrees C resulted in a 2-mu m thick oxide, whereas the 600 degrees C exposure resulted in a 100-nm thick oxide. Both oxides were layered, with an Fe-Al spinel on top, and an alumina layer toward the metal. In the 600 degrees C exposed material, there was a Cr-rich oxide layer between the spinel and the alumina. Metallic lead particles were found in the inner and middle parts of the oxide, related to pores. The combination of the experimental techniques, focusing on atom probe tomography, and the interpretations that can be done, are discussed in detail.