Oxygen diffusion studies in oxide scales thermally grown or deposited on mechanically loaded metallic surfaces (MS-P2)

Berger, Pascal; Gaillet, Laurent; Tahhann, R. El; Moulin, Gérard; Viennot, Marc

doi:10.1016/s0168-583x(01)00591-2

Cited by 15 publications

(6 citation statements)

References 7 publications

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“…s −1 for Ni (111). 24 This value is comparable to the values we determined in the temperature range 600-700 • C. Figure 6 exhibits the Arrhenius's plot of our effective diffusion coefficients associated with the value determined by Berger et al 24 The so-calculated activation energy is 230 kJ . mol −1 .…”

Section: Discussionsupporting

confidence: 83%

“…[20][21][22][23][24] As far as we know, only two studies concern the oxygen diffusion in polycrystalline NiO scales. 23,24 The aim of this work was to study the oxidation of Ni in air under atmospheric pressure over the temperature range 600-1000 • C, and to rely kinetics and morphologies of the NiO scales to 16 O 2 / 18 O 2 oxidation tests followed by secondary ion mass spectrometry (SIMS) analyses. Oxygen diffusion coefficients (effective, bulk and grain boundary diffusion coefficients) in thermally grown NiO scales were calculated and compared to the oxygen as well as the nickel diffusion coefficients from the literature.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen Transport during the High Temperature Oxidation of Pure Nickel

2005

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The high temperature oxidation of nickel has been investigated in air under atmospheric pressure in the temperature range 600-900 • C. The oxidation kinetic curves deviate from the parabolic law for temperatures over 800 • C. The observation of scale morphologies and the use of two stage oxidation experiments under 16 O 2 / 18 O 2 atmospheres showed that oxygen transport through the NiO scale had to be taken into consideration during the oxidation process. Despite the main outward diffusion of Ni species through the oxide scale, the inward oxygen diffusion at lower temperatures ( <800 • C) or the oxygen transport, probably as molecular species, via pores or microcracks were found to play a major role in the formation of duplex oxide scales, made of small equiaxed oxide grains at the metal/oxide interface overgrown by larger columnar grains at the gas/oxide interface. Oxygen diffusion coefficients into thermally grown NiO scales were determined and compared to the values of Ni diffusion coefficients from the literature.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Oxygen Transport during the High Temperature Oxidation of Pure Nickel

2005

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“…The difference of approximately two orders of magnitude is assumed to reflect the effect of applied load and deformation around the crack tip. Similar effects are expected to apply for oxygen diffusion, as it has been shown in the work of Berger et al [26] that oxygen diffusivity in NiO increases by two orders of magnitude under a constant stress.…”

Section: Oxide Growth and Kineticssupporting

confidence: 75%

Intergranular crack tip oxidation in a Ni-base superalloy

et al. 2013

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High temperature intergranular crack tip oxidation under a single 600 s long sustained tensile load at 700 °C was studied for the Ni-base superalloy Allvac 718Plus. High-resolution analytical techniques showed oxidation to take place at and immediately ahead of the tip of an open crack, forming a closed but layered oxide structure about the prior (now oxidized) grain boundary. Near the prior grain boundary the oxide is Ni-rich with a Co-enriched layer furthest away from the metal and a Feenriched region below this. A Cr-rich oxide is present below the outer Ni-rich oxides throughout the crack, also in the direction of crack growth. This is believed to have a hindering effect on oxidation ahead of the crack. Ni 3 (Nb,Al) γ' precipitates close to the grain boundaries were found to oxidize and form regions of near-stoichiometric NiO within the oxide layers. Remaining constituents of γ' (e.g. Al and Nb) were found to be enriched in the surrounding oxidized matrix and also to produce thin oxide layers near the interface between unoxidized metal and the Cr-rich oxide. The formation of the crack tip oxides is discussed with regard to thermodynamics, kinetics and the influence of applied mechanical load.

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“…Mechanical deformation was shown to play a significant role in oxidation and corrosion damage for nickel and its alloys [13][14][15][16][17][18]. For instance, Moulin et al [13] studied the influence of external mechanical loading on oxygen diffusion during nickel oxidation.…”

Section: Introductionmentioning

confidence: 99%

“…Oxygen enrichment was observed in the oxide scale under mechanical loading and the ingress of oxygen in the substrate beneath the oxide scale became easier in the presence of a constant tensile load (creep). Berger et al [14,15] reported that the application of a constant load induced multiple cracks at the surface of nickel oxide scale and an increase of oxygen diffusivity by two orders of magnitude, although the enhancement of oxygen diffusivity decreased with the further increase of load level. The oxidation kinetics curves gained by thermogravimetric analysis indicated that the oxidation rate of pure nickel was accelerated by both tensile and compressive external stress [16].…”

Section: Introductionmentioning

confidence: 99%

Oxygen diffusion and crack growth for a nickel-based superalloy under fatigue-oxidation conditions

Karabela

Lin

et al. 2013

Materials Science and Engineering: A

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Advanced microscopy characterisation and numerical modelling have been carried out to investigate oxygen diffusion and crack growth in a nickel-based superalloy under fatigue-oxidation conditions. Penetration of oxygen into the material and the associated internal oxidation, which leads to material embrittlement and failure, have been found from Focused Ion Beam (FIB) examinations. Applied fatigue loading tends to enhance the extent of internal oxidation for temperatures at 750°C and above. Using a submodelling technique, finite element analyses of oxygen penetration at grain level have been carried out to quantify the fatigue-oxidation damage and calibrate the diffusion parameters based on the measurements of maximum depth of internal oxidation. The grain microstructure was considered explicitly in the finite element model, where the grain boundary was taken as the primary path for oxygen diffusion. A sequentially coupled mechanical-diffusion analysis was adopted to account for the effects of deformation on diffusion during fatigue loading, for which the material constitutive behaviour was described by a crystal plasticity model at grain level. Prediction of oxidation-assisted crack growth has also been carried out at elevated temperature from the finite 2 element analyses of oxygen diffusion near a fatigue crack tip. A failure curve for crack growth has been constructed based on the consideration of both oxygen concentration and accumulated inelastic strain near the crack tip. The predictions from the fatigue-oxidation failure curve compared well with the experimental results for triangular and dwell loading waveforms, with significant improvement achieved over those predicted from the viscoplastic model alone.

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Oxygen diffusion studies in oxide scales thermally grown or deposited on mechanically loaded metallic surfaces (MS-P2)

Cited by 15 publications

References 7 publications

Oxygen Transport during the High Temperature Oxidation of Pure Nickel

Oxygen Transport during the High Temperature Oxidation of Pure Nickel

Intergranular crack tip oxidation in a Ni-base superalloy

Oxygen diffusion and crack growth for a nickel-based superalloy under fatigue-oxidation conditions

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