The growth of protective ultra-thin alumina layers on γ-TiAl(111) intermetallic single-crystal surfaces

Maurice, Vincent; Despert, G.; Zanna, Sandrine; Josso, Pierre; Bacos, M.-P.; Marcus, Philippe

doi:10.1016/j.susc.2005.09.011

Cited by 45 publications

(41 citation statements)

References 28 publications

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“…Since the surface is terminated with Al, Ga and Ge, the onset of oxidation may be governed by the interaction with A elements. It is well known that Al-containing phases, such as TiAl [37], CoAl [38], AlGaN/GaN heterostructures [39] and NiCoCrAlYSiB [40] form Al 2 O 3 surface passivating layer hindering further oxidation. Hence, the Al terminated M 2 AlC(0 0 0 1) may also be passivated by Al 2 O 3 .…”

Section: Resultsmentioning

confidence: 99%

Surface energy of M2AC(0001) determined by density functional theory (M=Ti,V,Cr; A=Al,Ga,Ge)

et al. 2007

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Section: Resultsmentioning

confidence: 99%

Surface energy of M2AC(0001) determined by density functional theory (M=Ti,V,Cr; A=Al,Ga,Ge)

et al. 2007

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“…The procedure allowing us to calculate the equivalent thickness of the alumina layer from the Al 2p 3+ to Al 2p 0 peak intensity ratio and the composition of the modified alloy region underneath the oxide from the Ni 3p 0 to Al 2p 0 peak intensity ratio (assuming an homogeneous depth distribution in the metallic phase) has been described previously. 19 The O-Al stoichiometric ratio of the alumina layer was calculated from the intensity ratio of the O 1s to Al 2p 3+ peaks. This required the calibration of the transmission factor ratio (T O 1s / T Al 2p ) of the spectrometer that was made using a bulk boehmite (AlOOH) sample.…”

Section: Methodsmentioning

confidence: 99%

Modifications and Growth Mechanisms of Ultrathin Aluminum Oxide Films on NiAl in Water

et al. 2010

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X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) have been combined to study the modifications and growth of alumina thin films on NiAl(001) induced by exposure to water vapor at low pressure (10 -6 mbar) and by immersion in ultrapure liquid water at room temperature. The film thickness and stoichiometry, as well as the alloy composition changes, were analyzed by angle-resolved XPS measurements. Ultrathin (∼0.7 nm) hydroxylated native oxide films were compared to thicker (∼4 nm) anhydrous and oxygendeficient thermal oxide films grown at 900°C under low air pressure (10 -4 mbar). The results show that immersion in liquid water causes the formation of one to two equivalent additional monolayers of aluminum oxide at the interface between the native oxide film and the alloy, suggesting anion transport along the oxide/ alloy interface after entry at intergranular oxide sites. The hydroxylated oxide surface remains unchanged. In contrast, immersion of the thicker thermal oxide films in liquid water causes the formation of ∼3 equivalent additional aluminum oxide monolayers at the oxide/water interface, indicating cation transport through the film. AFM suggests a preferential growth at the boundaries between the oxide grains due to faster ion transport. The ∼4 nm thick thermal oxide film is inert when exposed to water at low vapor pressure (10 -6 mbar) confirming the pressure gap for the water-induced modifications of transitional alumina films. Exposure to ambient air partially annihilates the oxygen deficiency observed after formation as shown by the variation of the O-Al stoichiometry and core level shift effects.

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“…6 Furthermore, differences in the oxidation kinetics of the alloy constituents results in the formation of an oxide layer that is almost entirely composed of the constituent having higher oxidation rate. 7 Similarly, there exists a critical composition of alloy ͑often equimolar͒ for which oxidation results in the formation of mixed oxides. 8 Phase stability of the binary oxides is another issue which limits the compositional tuning to high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Compositional tuning of ultrathin surface oxides on metal and alloy substrates using photons: Dynamic simulations and experiments

et al. 2010

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We report on the ability to modify the structure and composition of ultrathin oxides grown on Ni and Ni-Al alloy surfaces at room temperature utilizing photon illumination. We find that the nickel-oxide formation is enhanced in the case of oxidation under photo-excitation. The enhanced oxidation kinetics of nickel in 5% Ni-Al alloy is corroborated by experimental and simulation studies of natural and photon-assisted oxide growth on pure Ni͑100͒ surfaces. In case of pure Ni substrates, combined x-ray photoelectron spectroscopy analysis, and atomic force microscope current mapping support the deterministic role of the structure of nickel passiveoxide films on their nanoscale corrosion resistance. Atomistic simulations involving dynamic charge transfer predict that the applied electric field overcomes the activation-energy barrier for ionic migration, leading to enhanced oxygen incorporation into the oxide, enabling us to tune the mixed-oxide composition at atomic length scales. Atomic scale control of ultrathin oxide structure and morphology in the case of pure substrates as well as compositional tuning of complex oxide in the case of alloys leads to excellent passivity as verified from potentiodynamic polarization experiments.

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The growth of protective ultra-thin alumina layers on γ-TiAl(111) intermetallic single-crystal surfaces

Cited by 45 publications

References 28 publications

Surface energy of M2AC(0001) determined by density functional theory (M=Ti,V,Cr; A=Al,Ga,Ge)

Surface energy of M2AC(0001) determined by density functional theory (M=Ti,V,Cr; A=Al,Ga,Ge)

Modifications and Growth Mechanisms of Ultrathin Aluminum Oxide Films on NiAl in Water

Compositional tuning of ultrathin surface oxides on metal and alloy substrates using photons: Dynamic simulations and experiments

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