Observations of Chromium-Oxide Films Containing Cerium and Yttrium Using Transmission Electron Microscopy

摘要

Samples of a pure Fe-26%Cr alloy were sputter-coated with a 4-nm layer of CeO_2 or Y_2O_3, then oxidized at 900℃ in 5x10~(-3) ton of oxygen. The oxide scale was removed from the substrate by dissolution of the alloy substrate in a solution of iodine in anhydrous methanol and examined in a transmission electron microscope to determine the microstructure of the oxide and the phases present in the scale. The phases CeCrO_3 (space group 62, Pnma and space group 221, Pm3m), YCrO_3 (space group 62, Pnma), and Y_2O_3 (space group 164, P3m1) were found in the oxide scale in the initial stages of oxidation. The relevance of these species in the reactive-element effect is discussed.