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  • 1
    Electronic Resource
    Electronic Resource
    Compositional changes in the underlying alloy produced by the oxidation of Ni-Cr alloys (1978)
    Springer
    Oxidation of metals 12 (1978), S. 439-449 
    Details
    ISSN: 1573-4889
    Keywords: alloy oxidation ; Ni-Cr alloys ; diffusion ; depletion zones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Compositional changes in the alloy beneath scales have been examined for the oxidation of Ni-27.4%Cr and Ni-40.2% Cr in 1 atm oxygen in the temperature range 1073–1473°K. Calculations of the rate of approach of the interfacial alloy composition to a constant value are compared with experimental data. Theoretical chromium depletion profiles obtained using both a finite difference analysis and an analytical expression are shown to be essentially equivalent and in good agreement with experimental measurements. The consequences of alloy depletion for the scaling behavior, when the protective scale is ruptured, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612089
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  • 2
    Electronic Resource
    Electronic Resource
    The oxidation of Ni-70 wt.%Cr in oxygen between 1073 and 1473°K (1980)
    Springer
    Oxidation of metals 14 (1980), S. 263-277 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; Ni-Cr alloys ; two-phase alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation of the relatively simple, two-phase alloy Ni-70 wt.%Cr in oxygen between 1073 and 1473°K results in the formation of a Cr2O3 scale containing less than O.5 wt.% Ni in solid solution. The oxidation kinetics are irreproducible for an initial period, which is brief at 1073 and 1273°K but much more pronounced at 1473°K, both in duration and degree. This behavior is associated with the failure of the protective Cr2O3 scale. However, after longer periods a compact layer of Cr2O3 becomes established under isothermal conditions and results in a change to more reproducible kinetics, especially at 1073 and 1273°K. Oxidation causes chromium depletion and the formation of a single-phase zone which separates the scale and the two-phase bulk alloy. The depth of Cr2O3 internal oxide coincides with this zone. The oxidation behavior is compared with that of more Ni-rich, single-phase Ni-Cr alloys, with particular reference to the effects of the constitution of the underlying alloy and the integrity of the protective oxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00604568
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  • 3
    Electronic Resource
    Electronic Resource
    Morphologies of uniform adherent scales on binary alloys (1981)
    Springer
    Oxidation of metals 16 (1981), S. 1-28 
    Details
    ISSN: 1573-4889
    Keywords: Oxidation ; sulfidation ; scale morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The various scale morphologies arising from the oxidation and sulfidation of binary alloys are summarized. The relationships between simple single-phase morphologies and more complex multiphase, multilayer cases are arranged diagrammatically by defining qualitatively the restrictions on the thermodynamic stabilities and transport properties of the oxidation products which result in increasing scale complexity. Factors which can cause the formation of nonuniform scales are considered briefly. Oxide and sulfide scales on binary alloys of Fe, Co, Ni, Cu, Mn, Cr, and Al are discussed semiquantitatively in an attempt to identify the important properties which cause changes in oxidation rates and morphologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00603743
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  • 4
    Electronic Resource
    Electronic Resource
    The formation of solid solution oxides during internal oxidation (1981)
    Springer
    Oxidation of metals 16 (1981), S. 159-174 
    Details
    ISSN: 1573-4889
    Keywords: Internal oxidation ; Ni alloys ; Fe-Mn alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The diffusion processes occurring when binary alloys react with oxygen to form an oxide that contains both alloy components in solid solution, either exclusively as internal oxide or in combination with a surface scale, have been analyzed and compared with experimental results for Fe-Mn and Ni-Co alloys. The experimental results available for the Fe-Mn system were obtained under conditions of exclusive internal oxidation, and good agreement was obtained between calculated and experimental results. In the Ni-Co system, a surface scale and a zone of internal oxidation develop. Agreement between calculated and experimental depths of internal penetration is acceptable if the diffusivity of oxygen in the alloy is 3.8×10−6 cm2/sec at 1100°C. Agreement between calculated and experimental concentration profiles is not very good.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00603750
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  • 5
    Electronic Resource
    Electronic Resource
    Oxidation of nickel-manganese alloys in the temperature range 873–1273 K (1982)
    Springer
    Oxidation of metals 18 (1982), S. 295-314 
    Details
    ISSN: 1573-4889
    Keywords: Nickel-manganese alloys ; oxidation ; solid solution scales ; internal oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ni-Mn alloys containing up to 38% Mn have been oxidized in pure oxygen between 873 and 1273 K and the parabolic rate constants measured. The scale morphologies and oxide compositions are interpreted in terms of modifications to the scale on pure Mn caused by the presence of Ni. The scales are composed predominantly of two layers at all temperatures, giving the sequences of phases alloy/cubic monoxide (Ni, Mn)O/ternary spinel, with the cubic (Ni, Mn)O layer always having the greater thickness. There is limited evidence for a third, very thin, outer layer in the scales on all alloys at 873 K and for Ni-38%Mn at 1073 K, which is tentatively considered to be Mn2O3, giving layers in the order alloy/cubic monoxide/ternary spinel/Mn2O3, by analogy with the scale formed on pure Mn. The distribution of the alloy components in the scale is discussed in relation to the Ni-Mn-O phase diagram and in terms of recent theoretical treatments of solid solution scale formation on binary alloys, as far as the available diffusion data allow. The occurrence of internal and intergranular oxidation and the formation of a Mn-depleted zone coincident with the band of uniform internal oxide are considered briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656573
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  • 6
    Electronic Resource
    Electronic Resource
    Role of kinetic effects on metal partition at the alloy-scale interface during the oxidation of alloys (1975)
    Springer
    Oxidation of metals 9 (1975), S. 215-223 
    Details
    ISSN: 1573-4889
    Keywords: cation diffusion ; oxidation ; metal partition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An alternative mass balance at the alloy-scale interface is proposed for the Wagner theory of binary alloy oxidation. A simple relation between the bulk composition of the alloy and the scale composition at the alloy-scale interface, ξ′, is derived in terms of the transport properties of the scale and the limit of application of the relation defined. There is good agreement between calculated and measured values of ξ′.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613274
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  • 7
    Electronic Resource
    Electronic Resource
    Multilayer scale formation during the sulfidation of nickel (1975)
    Springer
    Oxidation of metals 9 (1975), S. 473-496 
    Details
    ISSN: 1573-4889
    Keywords: nickel ; sulfidation ; multilayer scale ; diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The reaction between pure nickel and sulfur vapor has been studied over the temperature range 380–475° C. A scale consisting of four separate layers is formed and the growth of the three outer layers obeys parabolic kinetics. The innermost layer grows only in the very early stages, after which the thickness remains approximately constant. The layers have been identified as three different sulfides-Ni3S2, which forms the two inner layers, Ni7S6, and NiS. The three outer layers grow with preferred orientations; growth of the Ni3S2 and NiS layers is with the basal planes of their hexagonal structures parallel to the nickel substrate. The formation of the scale can be described in terms of a diffusion-controlled process and the same basic process continues after scale-metal separation occurs. The description of scale growth is combined with experimental data to calculate the diffusion coefficient of nickel ions in each phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00603855
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  • 8
    Electronic Resource
    Electronic Resource
    The morphological and structural development of internal oxides in nickel-aluminum alloys at high temperatures (1982)
    Springer
    Oxidation of metals 18 (1982), S. 127-146 
    Details
    ISSN: 1573-4889
    Keywords: Internal oxidation ; nickel-aluminum alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The formation and development of internal oxides in Ni-Al alloys containing 1–4 wt.% Al in Ni-NiO packs and in 1 atm oxygen at 800 to 1100°C have been studied. The internal oxide particles were relatively fine, closely spaced, and mainly acicular, although more granular near the surface. They were identified as Al2O3 at the advancing front, but NiAl2O4 at the surface and at a significant distance from that surface. Growth of internal oxide particles resulted in the development of significant compressive stresses in the internal oxide zone when formed in Ni-NiO packs. These stresses led to grainboundary sliding at the higher temperatures and extrusion of weak, internal oxide-denuded zones adjacent to alloy grain boundaries. At the lower temperatures, these stresses also resulted in significant preferential penetration of oxides down grain boundaries and sub-grain boundaries. Stress development and resulting phenomena were much less significant during oxidation in 1 atm oxygen because vacancies injected from the external NiO scale accommodated the volume increase during growth of internal oxide particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00662034
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  • 9
    Electronic Resource
    Electronic Resource
    Alloy depletion profiles resulting from the preferential removal of the less noble metal during alloy oxidation (1978)
    Springer
    Oxidation of metals 12 (1978), S. 413-438 
    Details
    ISSN: 1573-4889
    Keywords: alloy oxidation ; diffusion ; alloy depletion profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The assumptions involved in Wagner's original treatment of alloy depletion profiles are examined and found to be acceptable for many situations. Finite difference analyses do not result in profiles which are significantly different from those obtained by the much simpler analytical solution once steady-state parabolic growth is established. Consequently an analytical solution is preferred and its combination with the classical Wagner expression for scale growth leads to a unified description of alloy oxidation when only the least noble metal is oxidized. The description is tested for an Fe-27.4wt.% Cr alloy oxidized at 1273°K and agreement between theoretical and experimental results is satisfactory. Alternative treatments of alloy oxidation which require that there be no recession of the alloy-scale interface are discussed and it is concluded that this assumption is unnecessarily restrictive in many cases. Suggestions that the oxidation of austenitic steels is controlled by diffusion in the alloy and that an interfacial transfer step is of importance in determining the oxidation rate in some cases are shown to be based on invalid assumptions. An analytical solution to the diffusion equation is developed for the case when a phase change occurs in the alloy because of less noble metal depletion and an expression is also presented for the profile developed in the limiting case where depletion is determined by scale evaporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612088
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  • 10
    Electronic Resource
    Electronic Resource
    Development of preferential intergranular oxides in nickel-aluminum alloys at high temperatures (1982)
    Springer
    Oxidation of metals 18 (1982), S. 93-113 
    Details
    ISSN: 1573-4889
    Keywords: Intergranular oxidation ; nickel-aluminum alloys ; internal oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The development of intergranular oxides in dilute Ni-Al alloys containing 0.55–4.10% Al in Ni-NiO packs and in 1 atm oxygen at 800–1100°C has been examined. In the Ni-NiO packs, preferential intergranular oxide penetration as well as internal oxidation occurs in every case, except in the higher aluminum-containing alloys at 1100°C. Several different types of intergranular oxide morphology were observed, depending on alloy aluminum concentration and on temperature. The oxides in the more dilute alloys are thin and relatively continuous and are accompanied by preferential penetration of internal oxide particles in the adjacent grains. Thicker intergranular oxides are precipitated in the more concentrated alloys while, in some situations, numerous fine oxide particles are formed well ahead of the main intergranular oxide. The intergranular oxidation is facilitated by high stress development in the specimens due to increases in volume as internal and intergranular oxides are formed. These stresses create microvoids in the grain boundaries immediately ahead of the advancing internal and intergranular oxides, resulting in preferential nucleation and growth of further intergranular oxides. This is the case particularly at the lower temperatures where other stress-relief processes cannot operate. The resulting relatively continuous, incoherent intergranular oxide-metal interface allows a high flux of oxygen to the advancing intergranular oxide front. Preferential intergranular oxidation is much less extensive in the presence of a thickening external NiO scale, due to accommodation of the volume increases on internal oxide formation by vacancies injected into the alloy from the growing cationdeficient scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00662032
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