Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Atmospheric Corrosion of Magnesium Alloys: Influence of Temperature, Relative Humidity, and Chloride Deposition
Institut de la Corrosion, Brest.
Swedish Corrosion Institute, Stockholm.
Swedish Corrosion Institute, Stockholm.
2004 (English)In: Corrosion, ISSN 0010-9312, Vol. 60, no 4, 356-362 p.Article in journal (Refereed) Published
Abstract [en]

Laboratory tests have been performed to determine how climatic parameters, e.g., relative humidity, temperature, and the amount of sodium chloride (NaCl), influence the corrosion rate of magnesium alloys AZ91D (UNS M11916) and AM50 (UNS M10500). The effect of the surface state also has been investigated. The exposures were performed at 75%, 85016, and 95% relative humidity (RH) and at 25degreesC and 35degreesC. The amount of NaCl ranged from 14 mug cm(-2) to 240 mug cm(-2). The corrosion rate of both materials increased as a function of temperature, RH, and amount of NaCl. A strong influence of the surface state, i.e., as-cast or polished, was observed mainly due to the combined effect of an active surface layer and the roughness of as-cast surfaces.

Place, publisher, year, edition, pages
2004. Vol. 60, no 4, 356-362 p.
Keyword [en]
Atmospheric corrosion; Automobiles; Chlorine; Climatic parameters; Magnesium alloys; Relative humidity
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-7681ISI: 000220794900004OAI: oai:DiVA.org:kth-7681DiVA: diva2:12780
Note
QC 20100802Available from: 2007-11-21 Created: 2007-11-21 Last updated: 2010-08-02Bibliographically approved
In thesis
1. The Atmospheric Corrosion of Magnesium Alloys: Influence of Microstructure and Environments
Open this publication in new window or tab >>The Atmospheric Corrosion of Magnesium Alloys: Influence of Microstructure and Environments
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The low density and high specific strength of magnesium alloys have created a great deal of interest in the use of these alloys in the automotive and aerospace industries and in portable electronics. All of these industries deal with applications in which weight is extremely important. However, an obstacle to overcome when using magnesium alloys in engineering applications are their unsatisfactory corrosion properties. This thesis is devoted to the atmospheric corrosion of the two magnesium alloys AZ91D and AM50, in particular the ways the microstructure and exposure parameters of these alloys influence their corrosion behaviour. The work includes both laboratory and field studies. The results obtained show that the microstructure is of vital importance for the corrosion behaviour under atmospheric conditions.

The microstructure of magnesium-aluminium alloys contains different intermetallic phases, e.g. Al8Mn5 and β-Mg17Al12. The local nobility of these intermetallic phases was measured on a submicron level in an atmospheric environment. It was shown that particles of the Al-Mn type exhibit the highest Volta potential among the microstructure constituents of the AZ91D magnesium alloy. Further, it was shown that the Volta potential was highly dependent on the aluminium content of the magnesiumaluminium phases in the surface layer.

When thin electrolyte layers are present, CO2 diffuses readily to the surface forming magnesium carbonate, hydromagnesite. The CO2 lowers the pH in areas on the surface that are alkaline due to the cathodic reaction. This stabilises the aluminium-containing surface film, the result being increased corrosion protection of phases rich in aluminium. Both in the laboratory and under field conditions the corrosion attack was initiated in large α-phase grains, which is explained by the lower aluminium content in these grains. The thin electrolyte film, which is formed under atmospheric conditions, decreases the possibility of galvanic coupling of alloy constituents located at larger distances from each other. Thus the cathodic process is in most cases located in the eutectic α-/β phase close to the α-phases, instead of in intermetallic Al-Mn particles, even though the driving force for the initiation of the corrosion attack in Al-Mn particles should be high, due to their high nobility.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. 53 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2007:75
Keyword
Materials science, metallurgy
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-4545 (URN)978-91-7178-799-6 (ISBN)
Public defence
2007-12-07, F3, KTH, Lindstedtsvägen 26, Stockholm, 13:00
Opponent
Supervisors
Note

QC 20100802

Available from: 2007-11-21 Created: 2007-11-21 Last updated: 2016-12-16Bibliographically approved

Open Access in DiVA

No full text

Other links

One Petro

Search in DiVA

By author/editor
Thierry, Domnique
In the same journal
Corrosion
Metallurgy and Metallic Materials

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 115 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf