Effect of Hydrogen and Absence of Passive Layer on Corrosive Properties of Aluminum Alloys

Włodarczyk, Paweł P.; Włodarczyk, Barbara

doi:10.3390/ma13071580

Cited by 8 publications

(11 citation statements)

References 32 publications

(36 reference statements)

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“…One type was η-phase (and its analogues) and rich in Mg, Cu, and Zn, it usually acted as anode during corrosion. The other type mainly contained Fe, Cu, and Al, and it usually acted as cathode during corrosion [10,11,18,24]. The EDS line scan results also indicate that both the anodic and cathodic phases in coarse grain zone have a bigger diameter as well as a higher alloying element The TEM equipped with EDS was used to measurements in order to quantitatively analyze the diameter and microchemistry of intermetallic phases in sintered alloys.…”

Section: Microstructure Of Alloysmentioning

confidence: 99%

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Passive Film Properties of Bimodal Grain Size AA7075 Aluminium Alloy Prepared by Spark Plasma Sintering

Tian

Kang

et al. 2020

Materials

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The bimodal-grain-size 7075 aluminium alloys containing varied ratios of large and small 7075 aluminium powders were prepared by spark plasma sintering (SPS). The large powder was 100 ± 15 μm in diameter and the small one was 10 ± 5 μm in diameter. The 7075 aluminium alloys was completely densified under the 500 °C sintering temperature and 60 MPa pressure. The large powders constituted coarse grain zone, and the small powders constituted fine grain zone in sintered 7075 aluminium alloys. The microstructural and microchemical difference between the large and small powders was remained in coarse and fine grain zones in bulk alloys after SPS sintering, which allowed for us to investigate the effects of microstructure and microchemistry on passive properties of oxide film formed on sintered alloys. The average diameter of intermetallic phases was 201.3 nm in coarse grain zone, while its vale was 79.8 nm in fine grain zone. The alloying element content in intermetallic phases in coarse grain zone was 33% to 48% higher than that on fine grain zone. The alloying element depletion zone surrounding intermetallic phases in coarse grain zone showed a bigger width and a more severe element depletion. The coarse grain zone in alloys showed a bigger electrochemical heterogeneity as compared to fine grain zone. The passive film formed on coarse grain zone had a thicker thickness and a point defect density of 2.4 × 1024 m−3, and the film on fine grain zone had a thinner thickness and a point defect density of 4.0 × 1023 m−3. The film resistance was 3.25 × 105 Ωcm2 on coarse grain zone, while it was 6.46 × 105 Ωcm2 on fine grain zone. The passive potential range of sintered alloys increased from 457 mV to 678 mV, while the corrosion current density decreased from 8.59 × 10−7 A/cm2 to 6.78 × 10−7 A/cm2 as fine grain zone increasing from 0% to 100%, which implied that the corrosion resistance of alloys increased with the increasing content of fine grains. The passive film on coarse grain zone exhibited bigger corrosion cavities after pitting initiation compared to that on fine grain zone. The passive film formed on fine grain zone showed a better corrosion resistance. The protectiveness of passive film was mainly determined by defect density rather than the thickness in this work.

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Section: Microstructure Of Alloysmentioning

confidence: 99%

“…The SPS sintered alloys maintain the microstructural difference of powders after sintering, because of the low sintering temperature and fast heating rate [ 10 , 11 ]. The size of metallic powders can change the microstructures of sintered aluminium alloys and, thus, affects their mechanical and corrosion performance [ 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Passive Film Properties of Bimodal Grain Size AA7075 Aluminium Alloy Prepared by Spark Plasma Sintering

Tian

Kang

et al. 2020

Materials

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“…Diffusion activation energy of Al is less than diffusion activation energy of Cu (QAl<QCu) at temperatures from 160 o C to 250 o C for mutual diffusion in copper-aluminium thin film double layers, but the pre-exponential factors are different in tens times [14] It was founded experimentally, that copper electrochemical corrosion is higher than aluminium electrochemical corrosion in approximately two times at room temperature [3,4], so thin Al layer can prevent copper electrochemical corrosion. It was reported also about influence of hydrogen and absence of passive layer on corrosive properties of aluminium alloys [5].…”

Section: Introductionmentioning

confidence: 97%

Copper, Iron, and Aluminium Electrochemical Corrosion Rates and Intrinsic Diffusivitives Dependence on Temperature Investigations

Mv¹

2021

Preprint

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Our investigations show that electrochemical corrosion of copper is faster than electrochemical corrosion of aluminium at temperatures below 100oC. Literature data analysis shows that the Al atoms diffuse faster than the Cu atoms at temperatures higher than 475oC, Al rich intermetallic compounds (IMCs) are formed faster in the Cu-Al system, and the Kirkendall plane shifts toward Al side. Electrochemical corrosion occurs due to electric current and due to diffusion. An electronic devise working time, for example, depends on initial copper cover thickness on aluminium wire, connected to the electronic devise, temperature, and volume and dislocation pipe diffusion coefficients, so copper, iron, and aluminium electrochemical corrosion rates are investigated experimentally at room temperature and at temperature 100oC. Intrinsic diffusivities ratios of copper and aluminium at different temperatures and diffusion activation energies in the Cu-Al system are calculated by proposed here methods using literature experimental data. Dislocation pipe and volume diffusion activation energies of pure iron are calculated separately by earlier proposed method using literature experimental data. Aluminium dissolved into NaCl solution as the Al3+ ions at room temperature and at temperature 100oC, iron dissolved into NaCl solution as the Fe2+ (not Fe3+) ions at room temperature and at temperature 100oC, copper dissolved into NaCl solution as the Cu+ ions at room temperature and as the Cu+ and the Cu2+ ions at temperature 100oC. It is founded experimentally that copper corrosion is higher than aluminium corrosion, and ratio of electrochemical corrosion rates, kCu/kAl>1, decreases with temperature increasing, although iron electrochemical corrosion rate doesn’t depend on temperature below 100oC. It is obvious, because melting point of iron is more higher then melting point of copper or aluminium. It is calculated that copper electrochemical corrosion rate is approximately equal to aluminium electrochemical corrosion at temperature about 300oC, so copper can dissolve into NaCl solution mostly as the Cu2+ ions at temperature about 300oC. Ratio of intrinsic diffusivities, DCu/DAl <1, increases with temperature increasing, and intrinsic diffusivity of aluminium could be approximately equal to intrinsic diffusivity of copper at temperature about 460oC.

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“…The influence of hydrogen on metals was observed more than half a century ago (1960s) [1]. Hydrogen absorption in metals causes their "hydrogen embrittlement" [2][3][4], as well as changes in their electrochemical properties [5][6][7]. Hydrogen embrittlement causes a reduction in mechanical properties, while a change in electrochemical properties causes a reduction in the corrosive properties of metal alloys [5].…”

Section: Introductionmentioning

confidence: 99%

Deterioration of Property of Aluminum Alloys (EN AW-1050A, EN AW-5754 and EN AW-6060) by Absorbed Hydrogen

Włodarczyk

2022

Applied Sciences

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The paper reports the results of research on the effect of hydrogen penetration on the variations in the mechanical properties of selected aluminum alloys. As a result of the study, it can be observed that such variations contribute to the deterioration of mechanical properties, which, in turn, contributes to shortening the reliability time associated with the operation of aluminum alloy structures. The analysis involved structural aluminum alloys: EN AW-1050A, EN AW-5754 and EN AW-6060. Tensile strength and impact strength were measured. It was demonstrated that the absorption of hydrogen by the analyzed alloys led to the deterioration of mechanical properties of aluminum alloys. The performed measurements were compared to the previous research results regarding the influence of hydrogen on the deterioration of corrosion properties. The analysis of the influence of hydrogen on both issues allowed us to notice the reasons for shortening the operational reliability time of aluminum alloy parts. The awareness of the influence of hydrogen on aluminum alloys may contribute to the development of hydrogen systems or installations in which aluminum alloys can be used as a construction material, e.g., fuel cells, hydrogen supply pipes, block of combustion engine powered by hydrogen, etc. In the era of the development of zero-emission vehicles, the use of hydrogen as fuel is gaining more and more importance, where the influence of hydrogen on the properties of materials is an important issue.

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Effect of Hydrogen and Absence of Passive Layer on Corrosive Properties of Aluminum Alloys

Cited by 8 publications

References 32 publications

Passive Film Properties of Bimodal Grain Size AA7075 Aluminium Alloy Prepared by Spark Plasma Sintering

Passive Film Properties of Bimodal Grain Size AA7075 Aluminium Alloy Prepared by Spark Plasma Sintering

Copper, Iron, and Aluminium Electrochemical Corrosion Rates and Intrinsic Diffusivitives Dependence on Temperature Investigations

Deterioration of Property of Aluminum Alloys (EN AW-1050A, EN AW-5754 and EN AW-6060) by Absorbed Hydrogen

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