Effect of trace elements on electrochemical properties and corrosion of aluminium alloy AA3102

Gundersen, Jan Tore B.; Aytaç, Aylin; Ono, Satoshi; Nordlien, Jan Halvor; Nisancioḡl̄ū, Kemal

doi:10.1016/s0010-938x(03)00159-8

Cited by 38 publications

(45 citation statements)

References 10 publications

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“…This is verified also by the fact that the anodic polarization curve of activated Al-Pb alloys in chloride solution is not affected by the amount of Pb present in the alloy. 2 Pb concentrations in the range from 5 to 50 ppm were shown to give nearly the same polarization behavior. The time of heat-treatment at 600°C beyond a certain limit does not affect the polarization curve either, also indicating that the Pb film reaches a terminal thickness or continuity during the first 1 h of heat-treatment at 600°C, and it is not affected by prolonged heattreatment after that limit is reached.…”

Section: C319mentioning

confidence: 80%

“…The electrochemical apparatus and procedure used in these conventional electrochemical polarization tests ͑without in situ video filming͒ have been discussed in detail in earlier work. [1][2][3][4][5][6][7] Some of the samples were masked by acetone-based stop-off lacquer Miccrostop to expose areas of ϳ0.03 to 0.04 cm 2 for in situ observation under an optical microscope during the electrochemical polarization tests. The electrochemical cell used for these measurements was designed to expose the samples horizontally, with the test section facing upwards, for easy observation of the corroding surface by the optical microscope.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4][5][6] Activation was attributed to Pb segregating in the form of a nanosized metallic film, as well as particles, at the oxidemetal interface as a result of annealing at 600°C, and thereby destabilizing the oxide in chloride solution. [4][5][6][7] The lead particles were not as efficient activators as the film due to their poor wetting of the surface.…”

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confidence: 99%

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Multilayer Corrosion of Aluminum Activated by Lead

Anawati

Graver

Nordmark

et al. 2010

J. Electrochem. Soc.

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Segregation of Pb as a nanofilm between the thermal oxide and the metal substrate as a result of high temperature heat-treatment is known to activate aluminum alloys anodically in chloride solution. The relationship between the oxidation peaks in the polarization curve and corrosion morphology was investigated by the use of a video technique during electrochemical polarization. A model binary Al-Pb alloy containing 20 ppm Pb, which was annealed at 600°C, showed two oxidation peaks at Ϫ0.95 and Ϫ0.88 V SCE . The video measurements revealed superficial etching of the surface by selective oxidation of the aluminum metal twice, followed each time by repassivation, as the two oxidation peaks were resolved during anodic potentiodynamic sweep. Ex situ scanning and transmission electron microscopy of the corroded specimens indicated that the first layer of etching followed the Pb film and undermined the thermal oxide, which remained attached to the metal surface at discrete locations, thereby forming a crevice. The second layer of attack was caused by crevice corrosion of the aluminum substrate in the crevice formed by the preceding oxidation process, which resulted in the removal of the attached thermal oxide film. The exposed aluminum substrate started to pit as the pitting potential was finally exceeded. © 2010 The Electrochemical Society. ͓DOI: 10.1149/1.3478663͔ All rights reserved. Lead, which is present as a trace element in almost all aluminum alloys at the ppm level, has recently received significant attention because of its role in anodically activating aluminum alloys in chloride media.1-6 Activation was attributed to Pb segregating in the form of a nanosized metallic film, as well as particles, at the oxidemetal interface as a result of annealing at 600°C, and thereby destabilizing the oxide in chloride solution. [4][5][6][7] The lead particles were not as efficient activators as the film due to their poor wetting of the surface. The Pb film was formed by the entrapment of the Pb segregating during heat-treatment between the thermally formed ␥-Al 2 O 3 crystals and the aluminum substrate. Activation is characterized by a significant decrease in the corrosion potential of the Pb-containing alloy relative to pure aluminum and high anodic output at potentials below the pitting potential, where aluminum is expected to be passive, as shown in Fig. 1. For lead concentration from 5 to 50 ppm, the anodic polarization curve of activated aluminum is similar to the curve shown for 20 ppm Pb in Fig. 1. 4 The anodic polarization curve furthermore contains two apparent oxidation peaks, the nature of which is not yet understood. 5The purpose of the present work is to provide new electron-optical imaging and in situ video measurements for the development of corrosion morphology during potentiodynamic polarization of a model Al-Pb alloy in chloride solution to explain the cause of oxidation peaks and obtain a better understanding of the underlying corrosion mechanism. ExperimentalThe material used was a binary Al-Pb model al...

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Section: C319mentioning

confidence: 80%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Multilayer Corrosion of Aluminum Activated by Lead

Anawati

Graver

Nordmark

et al. 2010

J. Electrochem. Soc.

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“…Al alloys of 3xxx series contain 1-1.5% manganese (Mn), and Al/Mn intermetallic compounds might serve as vulnerable sites for attack of chloride ions [10,11,[16][17][18]. Moreover, it was found [16] that enrichment of lead at the metal-oxide interface would affect the electrochemical corrosion behavior of AA3102 Al alloy.…”

Section: Introductionmentioning

confidence: 99%

Role of second phase particles in pitting corrosion of 3003 Al alloy in NaCl solution

Liu

Cheng

2010

Materials & Corrosion

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The second phase particles in 3003 aluminum (Al) alloy were characterized by scanning electron microscope, energy-dispersive X-ray analysis and X-ray diffraction techniques. The role of second phase particles in Al alloy pitting corrosion was investigated by cyclic polarization measurement, and scanning vibrating electrode technique. Results demonstrated that the second phase particles in 3003 Al alloy are mainly Al x (Fe,Mn) intermetallics, with an average diameter of about 5 mm. The enrichment of Mn in second phase particles forms a galvanic cell effect relative to the adjacent Al alloy substrate. The initiation of pitting corrosion of 3003 Al alloy is the local dissolution of Al substrate around the second phase particles. When a sufficient amount of Al is dissolved away, the second phase particles drop off from the Al substrate, forming large pitting cavities that are usually linked each other.

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“…Similar observations have been done by applying GDOES during studies of 3xxx alloy surfaces [17] and this oxide replacement has been proposed as a possible reaction. [18] In many cases, it is important to know when the b to a-phase transformation is completed, and different techniques have been tested to evaluate this. [2] XRD is one possible technique, and with a penetration depth in Al of about 80 lm it is suitable for studies of the segregated surface zone, done in the present research.…”

Section: Discussionmentioning

confidence: 99%

Influence of Heat Treatment on the Surface Structure of 6082 Al Alloys

Bayat

Carlberg

2017

Metall Mater Trans A

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The b-Al 5 FeSi intermetallic phase and coarse Mg 2 Si particles have negative effects on extrudability and workability of 6xxx Al alloys billets. To achieve extruded products with a high surface quality, the as-cast billets are heat-treated before extrusion. During heat treatment, the undesired intermetallic particles, i.e., b-AlFeSi platelets are transformed to rounded a-Al(FeMn)Si intermetallic phases. Although the heat treatment of the bulk areas of the 6xxx Al alloys has been the focus of many previous studies, the process of phase transformation at the very surface has not been paid the same attention. In this study, microstructures of a homogenized billet of a 6082 alloy at the area very close to the surface were investigated. By comparing the X-ray diffraction patterns (XRD) of heat-treated samples as a function of different holding times, the gradual phase transformations could be followed, and using GDOES and map analysis by EDX, the alloying elemental redistribution was analyzed. Partial remelting and porosity growth was detected, and transformation rates were faster than in bulk material and from what is known from industrial processes.

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Effect of trace elements on electrochemical properties and corrosion of aluminium alloy AA3102

Cited by 38 publications

References 10 publications

Multilayer Corrosion of Aluminum Activated by Lead

Multilayer Corrosion of Aluminum Activated by Lead

Role of second phase particles in pitting corrosion of 3003 Al alloy in NaCl solution

Influence of Heat Treatment on the Surface Structure of 6082 Al Alloys

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