Structure and Stability of Anodic Films Formed on Aluminum Containing Dispersed Al3Fe Phase

Zahavi, J.; Zangvil, Avigdor; Metzger, M.

doi:10.1149/1.2131469

Cited by 24 publications

(12 citation statements)

References 1 publication

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“…Железо снижает коррозионную стойкость литейных алюминиевых сплавов системы Al-Si-Mg [4][5][6][7][8] и образует при концентрации выше 0,8 мас.% интерметаллидную фазу пластинчатой морфологии Al 5 SiFe, температура плавления которой составляет ~644 °С [9,10], т.е. она выше температуры ликвидуса литейного сплава.…”

Section: Introductionunclassified

Corrosion of an Aluminum Matrix Composite in situ Based on Al–7Si–1Fe Alloy

Finkelstein

Шак

Schaefer

2020

Russ. J. Non-ferrous Metals

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Приведены результаты сравнительного исследования коррозионной стойкости алюмоматричного композита, полученного методом продувки кислородом предварительно гидрогенизированного расплава на основе сплава Al-Si-Fe с содержанием железа более 1 %, предназначенного для литья под давлением, и сплава Al-7Si с 0,3 % Fe, модифицированного лигатурой 5Al-Ti в количестве 2 %. Коррозия в алюминиевых сплавах обусловлена нарушением сплошности оксидной пленки на некоторых фазах, прежде всего на фазе Al 5 SiFe. Пары образцов из композита и сплава сравнения диаметром 15 мм и длиной 50 мм подверглись испытаниям в 7 %-ном растворе солевого тумана NaCl в камере КСТ-1 на подвесках при температуре 22 °С в течение 300 ч. Полученные результаты показали близкие значения убыли массы образцов, несмотря на значительно более высокое содержание железа в материале, поскольку сформировавшиеся в расплаве при продувке кислородом частицы Al 2 O 3 размером 100-200 нм, осаждаясь на границах фаз, снижают площадь поверхности взаимодействия с коррозионной средой. Литературные данные показывают существенное отличие сопротивления коррозионному воздействию композитов ex situ от in situ вследствие различий в размерах и расположении в матрице упрочняющей фазы. Исследованный композиционный материал может быть рекомендован как коррозионно-стойкая альтернатива сплавам с повышенным содержанием железа, используемым для литья под давлением.

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Section: Introductionunclassified

Corrosion of an Aluminum Matrix Composite in situ Based on Al–7Si–1Fe Alloy

Finkelstein

Шак

Schaefer

2020

Russ. J. Non-ferrous Metals

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“…It is well known that the corrosion behavior of aluminum alloys is significantly affected by the presence of Fe-rich intermetallic particles which form inclusions in the host metal. [1][2][3][4] Such inclusions are the sites where corrosion pits form, although the chemical aspects of the process by which pit initiation occurs are not entirely clear. The present work investigated electrochemical behavior of Al 3 Fe inclusions and their role in creating locally aggressive chemical environment which influences local metal dissolution.…”

mentioning

confidence: 99%

Influence of Fe‐Rich Intermetallic Inclusions on Pit Initiation on Aluminum Alloys in Aerated NaCl

Park

Paik

Huang

et al. 1999

J. Electrochem. Soc.

197

126

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The role that Al3normalFe intermetallic inclusions play during initiation of pitting corrosion on aluminum alloys was investigated in 0.6 M NaCl. In aerated solutions microscopic observations showed the growth of cavities in the host metal adjacent to inclusions. The rest potential of synthetic Al3normalFe was measured in aerated and deaerated NaCl solutions over a range of bulk pH values between 2 and 12 and was found to act as a cathode. In aerated solutions rotating disk electrode experiments on synthetic Al3normalFe electrodes verified that the cathodic reaction corresponded to the reduction of dissolved oxygen. With scanning pH microelectrodes, measurements were carried out near synthetic Al3normalFe electrodes which were coupled in a galvanic cell with Al-6061 in NaCl solution. In addition, the pH measured over Al-6061 at a distance of 25–30 μm from the surface was observed to fluctuate between pH 4 and 8.5 for the first 2 h of immersion in NaCl solutions. Atomic force microscopy images of Al-6061 immersed in buffered aerated 0.6 M NaCl solution (pH 5.5) did not show any evidence of dissolution of the Al around intermetallics. These measurements support the view that Al3normalFe particles in Al-6061 serve as local cathodes, that a high pH develops around the intermetallic particles and creates cavities in the host metal, and that interactions among a cluster of intermetallic particles causes a large number of slowly dissolving alkaline cavities to evolve into a small number of rapidly dissolving acidic pits. © 1999 The Electrochemical Society. All rights reserved.

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“…Possibly, they are detached from the α-phase by the dissolution of α-phase around them. J. Zahavi et al [ 30 ] showed that Al alloys, including 0.4%-and 1.0%-Fe, have surfaces with patches of Al 3 F, and cavities formed by detachment of Al 3 Fe.…”

Section: Discussionmentioning

confidence: 99%

“…During anodizing, the number of patches of Al 3 Fe on the surface, decreases with anodizing time to develop cavities [ 30 ], and the second phase of Al/Fe is oxidized more rapidly [ 31 ]. This may deduce that the number of pits on the surface of Al alloys with t a = 1800 and 3600 s, is larger than that with t a = 0 (see Figure 2 , Figure 4 and Figure 5 ).…”

Section: Discussionmentioning

confidence: 99%

Changes in the Structure and Corrosion Protection Ability of Porous Anodic Oxide Films on Pure Al and Al Alloys by Pore Sealing Treatment

et al. 2022

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It is well known that corrosion protection of pure Al is enormously improved by the formation of porous anodic oxide films and by pore sealing treatment. However, the effects of anodizing and pore sealing on corrosion protection for Al alloys are unclear, because the alloying elements included in Al alloys affect the structure of anodic oxide films. In the present study, porous anodic oxide films are formed on pure Al, 1050-, 3003- and 5052-Al alloys, and pore sealing was carried out in boiling water. Changes in the structure and corrosion protection ability of porous anodic oxide films on pure Al and the Al alloys by pore sealing, were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). SEM observation showed that anodic oxide films formed on pure Al have a smooth surface after pore sealing, and that cracks are formed in anodic oxide films on 1050-, 3003- and 5052-aluminum alloys, after pore sealing. Corrosion protection after pore sealing increased with anodizing time on pure Al, but only slightly increased with anodizing time on the Al alloys.

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Structure and Stability of Anodic Films Formed on Aluminum Containing Dispersed Al3Fe Phase

Cited by 24 publications

References 1 publication

Corrosion of an Aluminum Matrix Composite in situ Based on Al–7Si–1Fe Alloy

Corrosion of an Aluminum Matrix Composite in situ Based on Al–7Si–1Fe Alloy

Influence of Fe‐Rich Intermetallic Inclusions on Pit Initiation on Aluminum Alloys in Aerated NaCl

Changes in the Structure and Corrosion Protection Ability of Porous Anodic Oxide Films on Pure Al and Al Alloys by Pore Sealing Treatment

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