Anodisation of aluminium alloy AA7075 – Influence of intermetallic particles on anodic oxide growth

Fan Zhang; Cem Örnek; Jan Olov Nilsson; Jinshan Pan

doi:10.1016/j.corsci.2019.108319

Anodisation of aluminium alloy AA7075 – Influence of intermetallic particles on anodic oxide growth

Fan Zhang^*, Cem Örnek, Jan Olov Nilsson, Jinshan Pan

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

52 Citations (Scopus)

Abstract

Microstructure and Volta-potential analyses were conducted to characterise intermetallic-particles (IMPs) in AA7075-T5. EIS and AFM were applied under operando-conditions to investigate anodisation processes. IMPs have pronounced influence on the growth of anodic aluminium oxide (AAO) films resulting in low charge-transfer resistance. Cu-bearing constituents show cathodic-character, whereas Mg₂Si and MgZn₂ particles show anodic-character. During anodisation, Al₇Cu₂Fe remain stable with peripheral-dissolution around boundary. De-alloying of S-phase particles leads to the detachment. Mg₂Si undergoes de-alloying at low potential, and re-passivation at high potential. MgZn₂ dissolves entirely upon anodization. Localised-dissolution in large-IMPs boundaries or nanometre-sized IMPs facilitates bubble evolution, confirming local breakdown of barrier-layer.

Original language	English
Article number	108319
Journal	Corrosion Science
Volume	164
DOIs	https://doi.org/10.1016/j.corsci.2019.108319
Publication status	Published - Mar 2020
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

Keywords

Anodization
In-situ EC-AFM
Intermetallic particles
Localised dissolution
Operando EIS
SKPFM

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title = "Anodisation of aluminium alloy AA7075 – Influence of intermetallic particles on anodic oxide growth",

abstract = "Microstructure and Volta-potential analyses were conducted to characterise intermetallic-particles (IMPs) in AA7075-T5. EIS and AFM were applied under operando-conditions to investigate anodisation processes. IMPs have pronounced influence on the growth of anodic aluminium oxide (AAO) films resulting in low charge-transfer resistance. Cu-bearing constituents show cathodic-character, whereas Mg2Si and MgZn2 particles show anodic-character. During anodisation, Al7Cu2Fe remain stable with peripheral-dissolution around boundary. De-alloying of S-phase particles leads to the detachment. Mg2Si undergoes de-alloying at low potential, and re-passivation at high potential. MgZn2 dissolves entirely upon anodization. Localised-dissolution in large-IMPs boundaries or nanometre-sized IMPs facilitates bubble evolution, confirming local breakdown of barrier-layer.",

keywords = "Anodization, In-situ EC-AFM, Intermetallic particles, Localised dissolution, Operando EIS, SKPFM",

author = "Fan Zhang and Cem {\"O}rnek and Nilsson, \{Jan Olov\} and Jinshan Pan",

note = "Publisher Copyright: {\textcopyright} 2019 Elsevier Ltd",

year = "2020",

month = mar,

doi = "10.1016/j.corsci.2019.108319",

language = "English",

volume = "164",

journal = "Corrosion Science",

issn = "0010-938X",

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T1 - Anodisation of aluminium alloy AA7075 – Influence of intermetallic particles on anodic oxide growth

AU - Zhang, Fan

AU - Örnek, Cem

AU - Nilsson, Jan Olov

AU - Pan, Jinshan

PY - 2020/3

Y1 - 2020/3

N2 - Microstructure and Volta-potential analyses were conducted to characterise intermetallic-particles (IMPs) in AA7075-T5. EIS and AFM were applied under operando-conditions to investigate anodisation processes. IMPs have pronounced influence on the growth of anodic aluminium oxide (AAO) films resulting in low charge-transfer resistance. Cu-bearing constituents show cathodic-character, whereas Mg2Si and MgZn2 particles show anodic-character. During anodisation, Al7Cu2Fe remain stable with peripheral-dissolution around boundary. De-alloying of S-phase particles leads to the detachment. Mg2Si undergoes de-alloying at low potential, and re-passivation at high potential. MgZn2 dissolves entirely upon anodization. Localised-dissolution in large-IMPs boundaries or nanometre-sized IMPs facilitates bubble evolution, confirming local breakdown of barrier-layer.

AB - Microstructure and Volta-potential analyses were conducted to characterise intermetallic-particles (IMPs) in AA7075-T5. EIS and AFM were applied under operando-conditions to investigate anodisation processes. IMPs have pronounced influence on the growth of anodic aluminium oxide (AAO) films resulting in low charge-transfer resistance. Cu-bearing constituents show cathodic-character, whereas Mg2Si and MgZn2 particles show anodic-character. During anodisation, Al7Cu2Fe remain stable with peripheral-dissolution around boundary. De-alloying of S-phase particles leads to the detachment. Mg2Si undergoes de-alloying at low potential, and re-passivation at high potential. MgZn2 dissolves entirely upon anodization. Localised-dissolution in large-IMPs boundaries or nanometre-sized IMPs facilitates bubble evolution, confirming local breakdown of barrier-layer.

KW - Anodization

KW - In-situ EC-AFM

KW - Intermetallic particles

KW - Localised dissolution

KW - Operando EIS

KW - SKPFM

UR - https://www.scopus.com/pages/publications/85075390610

U2 - 10.1016/j.corsci.2019.108319

DO - 10.1016/j.corsci.2019.108319

M3 - Article

AN - SCOPUS:85075390610

SN - 0010-938X

VL - 164

JO - Corrosion Science

JF - Corrosion Science

M1 - 108319

ER -

Anodisation of aluminium alloy AA7075 – Influence of intermetallic particles on anodic oxide growth

Abstract

Bibliographical note

Keywords

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