Corrosion Behavior of Aluminum‐Molybdenum Alloys in Chloride Solutions

Moshier, W. C.; Davis, Glyn; Ahearn, J. S.; Hough, H. F.

doi:10.1149/1.2100271

Cited by 69 publications

(58 citation statements)

References 11 publications

(15 reference statements)

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“…12,13 A recent paper showed how the corrosion and electrical properties of AlO x N y thin films changed as oxygen and nitrogen were added.…”

Section: 9mentioning

confidence: 99%

“…12,13 A recent paper showed how the corrosion and electrical properties of AlO x N y thin films changed as oxygen and nitrogen were added. 22 A pure Al thin film with very low O content exhibited pitting at a potential similar to that of pure Al whereas films of varying O and N content exhibited no pitting corrosion at all, even after polarization to high potentials.…”

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confidence: 99%

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Effect of Vacuum System Base Pressure on Corrosion Resistance of Sputtered Al Thin Films

Frankel

Chen

Gupta

et al. 2014

J. Electrochem. Soc.

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Pure aluminum (Al) thin films were sputter deposited under conditions of variable base pressure of the deposition tool. The purpose of the study was to identify if the base pressure had a key influence on the electrochemical properties, namely corrosion resistance, of the Al deposits. The corrosion resistance was found to increase with increasingly high base pressure (i.e. lower quality vacuum). Potentiodynamic polarization experiments, pit growth studies, TEM and XPS were employed. From the results is posited that improved corrosion resistance is due to the presence of oxygen (O) being incorporated into the films during deposition resulting an O-containing (i.e. Al-O) alloy. This effect is important to identify because of the many reports in the literature of high pitting potentials for Al thin films, from studies with widely varying base pressure. Vacuum system base pressure was found to have a large effect on the corrosion resistance. A maximum base pressure in the low 10 −7 Torr range is recommended to minimize oxygen uptake into the film. Corrosion of thin film metal samples deposited by sputter deposition or evaporation has attracted considerable attention because of the technological applications of thin films in the electronics industry. From a research perspective, thin films also provide unique opportunities for studying fundamental aspects of the pitting phenomenon and also for the investigation of non-equilibrium alloy compositions. Many papers report an increased corrosion resistance of thin films relative to bulk alloy counterparts, often expressed as an increase in the pitting potential, E pit .1-11 Other researchers have found E pit for thin films to be similar to bulk alloys of a similar composition. 12,13Several different reasons for the improved corrosion resistance of thin films have been offered. Liu and coworkers proposed that the increase in pitting resistance of Ni-based alloy thin films resulted from the nanocrystalline microstructure of the films. [4][5][6][7] Regarding the role of grain size on corrosion resistance, both increases and decreases in corrosion resistance with decreasing grain size have been reported, 14 with the phenomenon being closely related to test environment.15 Because a fine grain structure has more reactive sites with respect to oxide formation and film ion conduction, the relative rates of reaction in a given environment might be altered. However, it is unlikely that grain size variation alone can explain the very noble values of E pit that have been reported for some pure metal thin film samples.Factors other than grain size have been reported to result in ennobled E pit values in thin film samples. 16 For alloys that pit at specific sites in a heterogeneous microstructure, such as MnS particles in stainless steel, improved homogeneity achieved by sputtering can certainly improve the corrosion performance. This chemical effect, as opposed to a structural effect, has been invoked by some as an important factor when evaluating sputtered stainless steel or Fe-Cr al...

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“…12,13 A recent paper showed how the corrosion and electrical properties of AlO x N y thin films changed as oxygen and nitrogen were added.…”

Section: 9mentioning

confidence: 99%

mentioning

confidence: 99%

Effect of Vacuum System Base Pressure on Corrosion Resistance of Sputtered Al Thin Films

Frankel

Chen

Gupta

et al. 2014

J. Electrochem. Soc.

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“…16 Figure 5 shows that a Mo concentration of 13 atom % increased the pitting potential by over 600 mV relative to unalloyed aluminum. Moshier et al also used XPS to determine the composition of the passive films formed in 0.1 M KCl.…”

Section: Al-mo-moshier Et Al Conducted a Series Of Experiments Onmentioning

confidence: 99%

Graph Theory and the Passivity of Binary Alloys

McCafferty

2004

J. Electrochem. Soc.

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Graph theory has been employed to model the passivity or corrosion behavior in various electrolytes for the following binary alloys: W-Zr, Al-Zr, Al-Ti, Mn-Ti, Al-Mo, Ti-Zr, Cr-Ti, and Ti-Cr. Sixteen sets of binary alloys have now been modeled using this approach, and the correlation coefficient between the predicted critical alloy composition using the graph theory approach and the experimental alloy composition is 0.932. Conditions under which the graph theory approach is tenable and limitations of the method are also discussed.

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“…5,7 In the case of aluminum alloys, the alloying with transition metals to supersaturated solid solution concentrations exceeding equilibrium solubilities has been a successful approach for improving localized corrosion resistance. [11][12][13][14][15] Here, the native oxide formed on crystalline Al is already amorphous and the main benefits of nonequilibrium alloying derive from two broad concepts. Alloying elements available in solid solution may be incorporated into the oxide film to enhance its resistance to halide chemisorption and/or penetration.…”

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confidence: 99%

“…Alloying elements available in solid solution may be incorporated into the oxide film to enhance its resistance to halide chemisorption and/or penetration. 11,13 Alternatively, alloying elements in the underlying metallic substrate may reduce pit dissolution rates as a function of elec-trochemical potential, 16 increase the severity of critical depassivating pit solutions, or result in oxidized solute with limited solubility in the pit environment. 17 Ion implantation, codeposition by evaporation or sputtering, and rapid solidification are methods to obtain both nonequilibrium alloying and an amorphous condition.…”

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confidence: 99%

Nanocrystalline Al[sub 87]Ni[sub 8.7]Y[sub 4.3] and Al[sub 90]Fe[sub 5]Gd[sub 5] Alloys that Retain the Localized Corrosion Resistance of the Amorphous State

Sweitzer

Scully

Bley

et al. 1999

Electrochem. Solid-State Lett.

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The localized corrosion properties of Al 87 Ni 8.7 Y 4.3 and Al 90 Fe 5 Gd 5 , were investigated in the amorphous, high strength partially nanocrystalline, and fully crystalline states. The critical pitting potentials and pit growth behaviors of amorphous and nanocrystalline alloys were improved compared to high purity, polycrystalline Al in 0.6 M NaCl solution. Transition metal (TM) and rare earth additions (RE) were retained in solid solution in amorphous alloys and the remaining amorphous matrix of partially nanocrystalline alloys. Substantial TM and RE solute rejection occurred from nano-and microcrystals. Notably, the improved resistance to pitting was retained in the partially nanocrystalline condition, but was completely lost in the fully crystalline alloys. The opportunity exists to create partially nanocrystalline Al-TM-RE alloys of great strength with corrosion resistance equal to their amorphous counterparts. © 1999 The Electrochemical Society. S1099-0062(99)02-016-7. All rights reserved.Manuscript received February 2, 1999. Available electronically March 18, 1999. It is well established in the literature that glassy alloys and alloys with a low degree of crystallinity offer superior resistance to corrosion and vastly improved mechanical properties over their conventional counterparts. 1,2 Amorphous alloys often have corrosion resistance one to two orders of magnitude greater than polycrystalline alloys with the same alloy composition. 1,2 One theory links the improved resistance of amorphous alloys to their ability to promote amorphous oxide formation. In high temperature gas, vitreous or amorphous oxides offer improved oxidation resistance due to the absence of oxide grain boundaries which provide a rapid diffusion path for concentration gradient driven ion movement. 3,4 In the case of metal passivity in aqueous solutions, ion transport is mostly driven by the electric field across the oxide film. The lack of oxide grain boundaries may lower ion migration rates, rendering the passive film more protective. [3][4][5] The rapid transport and accumulation of cation vacancies at the oxide/metal interface is one theory accounting for oxide breakdown. 6 Moreover, vitreous oxides on amorphous alloys perform well due to enhanced bond flexibility since the vitreous or amorphous material can rearrange to accommodate lattice mismatch and strain between the oxide and the metal. 5,7 As a result of this flexibility, almost all surface atoms can bond with oxygen or OH -without requiring an optimal epitaxial relationship between an ordered metal substrate and oxide. 5 Intolerable changes in oxide/metal misfit strain with halide incorporation is another theory accounting for the rupture of protective oxide films on metals. 8 The improved corrosion resistance associated with the addition of 18% Cr to Fe is attributed, in part, to a change in the protective oxide structure from a well oriented spinel structure at 0-12% Cr to a noncrystalline structure at 18% Cr. 5 This disordering has been shown by low energy electr...

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Corrosion Behavior of Aluminum‐Molybdenum Alloys in Chloride Solutions

Cited by 69 publications

References 11 publications

Effect of Vacuum System Base Pressure on Corrosion Resistance of Sputtered Al Thin Films

Effect of Vacuum System Base Pressure on Corrosion Resistance of Sputtered Al Thin Films

Graph Theory and the Passivity of Binary Alloys

Nanocrystalline Al[sub 87]Ni[sub 8.7]Y[sub 4.3] and Al[sub 90]Fe[sub 5]Gd[sub 5] Alloys that Retain the Localized Corrosion Resistance of the Amorphous State

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