Characterization of the alumina film with cerium doped on the iron-aluminide diffusion coating

An iron-aluminide layer with a thin alumina film on the top as a composite tritium permeation barrier (TPB) coating was characterized under different oxidation conditions. The TPB coating was prepared initially on a China Low Activation Ferritic-Martensitic (CLAM) steel by a pack cementation aluminizing process and then an alumina film was formed on the surface of this iron-aluminide diffusion layer by an oxidizing process. To modify the properties of the FeAl/Al2O3 composite TPB coatings, the rare earth element (cerium) was introduced as a dopant while oxidizing. Characterization showed that a continuous oxide scale with a thickness of about 300–400nm was formed on the FeAl diffusion layer. The film was mainly composed of Al2O3 doped with a little CeO2. In addition, the concentration of α-Al2O3 increased with elevated temperature while oxidizing. The phase transformation behavior of alumina scale on the surface of an iron-aluminide layer was studied in this paper.