title: The reactive element effect of ceria particle dispersion on alumina growth: A model based on microstructural observations.
abstract: The oxidation kinetics of alumina-forming metals can be affected by adding a small amount of a reactive (normally rare earth) element oxide (RExOy) and the segregation of the reactive element (RE) ions to the growing alumina grain boundaries (GBs) has been considered as a responsible reason. However, this interpretation remains a controversial issue as to how RE ions are produced by RExOy which is thermodynamically and chemically stable in metals. The question is answered by a model that is based on transmission electron microscopy (TEM) investigation of a CeO2-dispersed nickel aluminide oxidized in air at 1100 °C. The CeO2 dispersion is incorporated into the alumina scale by the inward growth of inner α-Al2O3, where it partially dissolves producing tetravalent Ce cations which then transform to trivalent cations by trapping electrons. The trivalent cations segregate to the α-Al2O3 GBs and diffuse outward along first the GBs and later the twin boundaries (TBs) in the outer γ-Al2O3 layer, being precipitated as Ce2O3 particles near surface.
authors.affiliation: School of Materials Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.|Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.|Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: X
authors.initials: X
authors.lastname: Peng
authors.affiliation: Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: X
authors.initials: X
authors.lastname: Tan
authors.affiliation: Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: F
authors.initials: F
authors.lastname: Wang