Oxidation mechanisms of β-NiAl + Zr determined by SIMS

Prescott, R.; Mitchell, D. F.; Graham, M. J.; Doychak, J.

doi:10.1016/0010-938x(95)00034-h

Cited by 83 publications

(52 citation statements)

References 22 publications

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“…[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Such insights have proven particularly useful for understanding the influence of various alloying additions on film growth, and provide a basis for improved alloy design. For example, tracer studies of Al 2 O 3 -forming alloys with and without rare earth element dopants revealed beneficial effects related to more protective, oxygen inward growth mechanisms [e.g.…”

mentioning

confidence: 99%

Tracer Film Growth Study of Hydrogen and Oxygen from the Corrosion of Magnesium in Water

Brady

Fayek

Elsentriecy

et al. 2014

J. Electrochem. Soc.

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An isotopic tracer study of the film growth mechanism for pure magnesium, AZ31B, and ZE10A (Elektron 717, E717) magnesium alloys in water at room temperature was performed. A series of individual and sequential exposures were conducted in both H 2 18 O and D 2 16 O, with isotopic tracer profiles obtained using secondary ion mass spectrometry (SIMS). The water-formed films consisted primarily of partially hydrated MgO. The SIMS sputter depth profiles indicate that H and D penetrated throughout the film and into the underlying metal, particularly for the Zr-and Nd-containing E717 alloy. Film growth for the UHP Mg involved aspects of both metal outward diffusion and oxygen/hydrogen inward diffusion. In contrast, the film on the Al-containing AZ31B alloy grew primarily by inward oxygen and inward hydrogen diffusion. The 18 O and D profiles for the film formed on E717 were the most complex, with the 18 O data most consistent with inward lattice oxygen diffusion, but the D data suggests inward, short-circuit diffusion through the film. It is speculated that preferential inward short circuit hydrogen transport may have been aided by the presence of nano Zn 2 Zr 3 particles throughout the E717 film. Such hydrogen penetration may have implications from both a corrosion resistance and hydrogen storage perspective. Magnesium alloys are of great interest because they can be used to manufacture lightweight automotive and aircraft structural materials that reduce vehicle weight and improve fuel efficiency.1-3 However, the poor corrosion resistance of Mg is a major challenge.4-6 A key contributor to the poor corrosion resistance of Mg is the inability to establish and/or maintain protective surfaces films. Surface films formed on Mg under ambient air and water conditions typically consist of mixtures of Mg(OH) 2 and MgO, with small amounts of MgCO 3 often also reported.7-12 They provide adequate protection under some circumstances, but are particularly vulnerable to disruption by salt species.The ambient corrosion of Mg differs from many corrosion-resistant structural alloy classes in that the protective surface films can become quite thick, on the order of tens to hundreds of nanometers, rather than the few nanometers typically encountered for protective films on stainless steels, for example. As such, corrosion resistance is influenced not only by classical thin film electrochemical passivity considerations, but also thermodynamic and kinetic considerations typically encountered in thick-film (> 0.5 micron range), high-temperature alloy oxidation phenomena.Isotopic tracer studies have been widely applied to studies of the high-temperature oxidation of alloys (Al, Fe, Ni, and Zr base; SiC), with significant new insights gained regarding the growth mechanism of the oxide films. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Such insights have proven particularly useful for understanding the influence of various alloying additions on film growth, and provide a basis for improved alloy design. For examp...

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mentioning

confidence: 99%

Tracer Film Growth Study of Hydrogen and Oxygen from the Corrosion of Magnesium in Water

Brady

Fayek

Elsentriecy

et al. 2014

J. Electrochem. Soc.

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“…The specimens showed the expected [2] outer region consisting of relatively small alumina grains with some Zr or Hf oxide precipitates and voids. Underneath is a layer with larger Al 2 O 3 -oxide grains.…”

Section: Scanning Electron Microscopy and Atomic Force Microscopymentioning

confidence: 92%

“…For the past 25 years, it has been generally recognized that transport through a growing a-Al 2 O 3 scale takes place predominantly by the inward diffusion of O along grain boundaries when a reactive element (RE) is present [1][2][3][4][5][6][7][8][9][10][11]. Without a RE addition, a mixed Al and O growth was observed for a-Al 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

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Grain Boundary Chemistry and Transport Through Alumina Scales on NiAl Alloys

et al. 2017

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It is widely accepted that the growth of protective a-Al 2 O 3 scales on Nibased alloys is governed by the inward diffusion of oxygen through the oxide grain boundaries (GB). However, there is also some outward diffusion of metal ions to the surface, but it is difficult to quantify. In this work we apply atomic force microscopy, scanning electron microscopy and transmission electron microscopy to investigate the outward flux of Al, which manifests as the growth of small ridges along the alumina GBs after the removal of the outermost oxide layer by mechanical polishing or focused ion beam techniques followed by additional oxidation. As a model alumina-former, NiAl with Hf and Zr additions was investigated. In comparison to Zr, Hf was found to reduce the outward Al diffusion. This outward diffusion was six orders of magnitude smaller than the O inward diffusion.

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“…While the TGO is largely composed of alpha alumina, which is the most stable phase, it can also contain substantial amounts of mixed oxides, such as spinels of the type Ni (Cr,Al) 2 0 4 , or Cr 2 0 3 , etc. [6][7][8]. The TGO is a non-equilibrium region, and grows in the presence of oxygen that is continuously fed by the open channel YSZ layer.…”

Section: Mechanisms and Mechanics Of Failure Of Tbcsmentioning

confidence: 99%

Advanced Thermal Barrier Coating

Bhattacharya¹

2000

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Oxidation mechanisms of β-NiAl + Zr determined by SIMS

Cited by 83 publications

References 22 publications

Tracer Film Growth Study of Hydrogen and Oxygen from the Corrosion of Magnesium in Water

Tracer Film Growth Study of Hydrogen and Oxygen from the Corrosion of Magnesium in Water

Grain Boundary Chemistry and Transport Through Alumina Scales on NiAl Alloys

Advanced Thermal Barrier Coating

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