The nucleation and growth of oxide islands on aluminum

Hart, R. K.; Maurin, Jan K.

doi:10.1016/0039-6028(70)90182-2

Cited by 44 publications

(12 citation statements)

References 10 publications

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“…1,3,4,[6][7][8][9][17][18][19][20]38 In such a case the mismatch between the adjacent lattices of the two crystalline phases is accommodated by elastic deformation. Generally, the mismatch in the boundary is characterized by the mismatch values in two directions within the boundary.…”

Section: Mismatch Contribution To ͗M͘-͗mo X ͘ Interfacial Energymentioning

confidence: 99%

“…The crystalline oxide competing with the amorphous oxide ͕Al 2 O 3 ͖ of the same composition is ␥-Al 2 O 3 . 1,[17][18][19][20] First the difference in bulk, surface, and interfacial energies of the amorphous ͕Al 2 O 3 ͖ cell on the ͗Al͘ substrate and the corresponding crystalline ͗␥-Al 2 O 3 ͘ cell on the same substrate will be discussed. Then the stability of the oxide films is discussed as a function of growth temperature, oxide-film thickness, and crystallographic orientation of the ͗Al͘ substrate.…”

Section: Thermodynamics Of Amorphous and Crystalline Aluminum-oximentioning

confidence: 99%

“…In this case, the crystalline oxide ␥-Al 2 O 3 competes with the amorphous Al 2 O 3 oxide. 1,[17][18][19][20] The predictions, as obtained by application of the model to the Al-Al 2 O 3 system, are compared with experimental data obtained by transmission electron microscopy.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic stability of amorphous oxide films on metals: Application to aluminum oxide films on aluminum substrates

et al. 2000

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It has been shown on a thermodynamic basis that an amorphous structure for an oxide film on its metal substrate can be more stable than the crystalline structure. The thermodynamic stability of a thin amorphous metal-oxide film on top of its single-crystal metal substrate has been modeled as a function of growth temperature, oxide-film thickness, and crystallographic orientation of the metal substrate. To this end, expressions have been derived for the estimation of the energies of the metal-substrate amorphous-oxide film interface and the metal-substrate crystalline-oxide film interface as a function of growth temperature, and crystallographic orientation of the substrate ͑including the effect of strain due to the lattice mismatch͒. It follows that, up to a certain critical thickness of the amorphous oxide film, the higher bulk Gibbs free energy of the amorphous oxide film, as compared to the corresponding crystalline oxide film, can be compensated for by the lower sum of the surface and interfacial energies. The predicted occurrence of an amorphous aluminum-oxide film on various crystallographic faces of aluminum agrees well with previous transmission electron microscopy observations.

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Section: Mismatch Contribution To ͗M͘-͗mo X ͘ Interfacial Energymentioning

confidence: 99%

Section: Thermodynamics Of Amorphous and Crystalline Aluminum-oximentioning

confidence: 99%

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Thermodynamic stability of amorphous oxide films on metals: Application to aluminum oxide films on aluminum substrates

et al. 2000

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“…When it comes to the oxidation of pure aluminium, the literature is primarily focussed on oxidation in the solid state (see, e.g. [24,31,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]). …”

Section: Microstructural Observations Of Oxide Filmsmentioning

confidence: 99%

“…In solid-state oxidation of aluminium, it is generally observed that the initial oxide to form is amorphous [49][50][51][52][53][54][55]. When held at an elevated temperature, a crystalline oxide is observed [31,51,[54][55][56][57], often identified to be γ-alumina [31,51,54,55,[58][59][60][61].…”

Section: Microstructural Observations Of Oxide Filmsmentioning

confidence: 99%

A microstructural and kinetic study of molten aluminium oxidation in relation to dross formation

Bonner¹

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Oxidation and dross formation on molten aluminium is estimated to directly cause losses of tens of millions of dollars per annum to the Australian smelting industry. Although there has been significant study of molten aluminium oxidation over the past few decades, the formation mechanisms are still not fully understood. There is also lack of reliable and useful kinetic data that can be applied to computational simulations of industrial melt handling processes involving the oxidation of either quiescent pools or turbulent transfers of molten aluminium. There is additional uncertainty in the literature relating to the physical processes underlying molten aluminium oxidation, and the microstructural evolution of the growing oxide film. Past oxidation studies have been confounded by the detrimental effect of the pre-existing oxide ubiquitously present on aluminium specimens. Recent studies conducted at The University of Queensland have indicated a way forward in this respect, with the development of an experimental technique that enables the melt surface to be skimmed free of pre-existing oxide prior to each oxidation experiment. This project is based on previous outcomes and expands on them to create new insights into the oxidative behaviour of molten aluminium in response to various key parameters, such as melt temperature and isothermal holding time. It also aims to resolve some ambiguities in the literature.Melts of commercial purity aluminium were isothermally held at various temperatures ranging from 750°C to 900°C, and exposed to ambient air for times ranging up to ~20 h. The oxide grown on each melt was removed and treated to separate the oxide itself from the underlying aluminium metal, using a molten salt flux. The mass of oxide was then determined as a function of melt temperature and exposure time. These gravimetric experiments were complemented by morphological and microstructural characterization of grown oxide films, using scanning electron microscopy, transmission electron microscopy, and electron diffraction. These two approaches were combined to develop a simple kinetic model based on the parabolic rate law.The amount of oxide formed was found to be significantly lower than what has previously been reported, and was attributed to the removal of the pre-existing oxide. The amount of oxide that formed increased with increasing temperature, and the oxidation rate continuously decreased with increasing exposure time. These observations are consistent with diffusion-limited growth.Microstructural characterisation showed two stages of oxidation. In the early stage, nano-sized, planar, polyhedral crystallites of γ-alumina nucleate at the metal/oxide interface. In the later stage, flake-like γ-alumina crystallites were observed to grow outwards from the oxide/air interface. The time at which the second stage of growth became active decreased with increasing temperature, and the flake-like crystallites continued to increase in size with increasing exposure time.iii Crystallographic texture was obser...

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Directed Metal Oxidation

Jayaram¹,

Brandon²

2000

Handbook of Ceramic Hard Materials

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The nucleation and growth of oxide islands on aluminum

Cited by 44 publications

References 10 publications

Thermodynamic stability of amorphous oxide films on metals: Application to aluminum oxide films on aluminum substrates

Thermodynamic stability of amorphous oxide films on metals: Application to aluminum oxide films on aluminum substrates

A microstructural and kinetic study of molten aluminium oxidation in relation to dross formation

Directed Metal Oxidation

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