Aluminum grain boundary decohesion by dense sodium segregation

Shengjun Zhang, Oleg Y. Kontsevoi, Arthur J Freeman, Gregory B. Olson

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Despite numerous investigations, grain boundary (GB) embrittlement of metallic structural materials is a poorly understood fundamental phenomenon in materials science. One of the well-known examples is that minute traces of sodium induce an embrittlement in aluminum alloys that results in drastic failure and limits their applications. From first-principles density function theory calculations, we found that sodium atoms densely segregate and neighbor into the 5(012)[100] GB in aluminum with large segregation energies and that the GB strength drops to only one fifth of the strength of the clean Al GB. Gradual sodium segregation leads to not only a large GB expansion but also to the replacement of stronger Al-Al metallic bonds with the weaker Al-Na mixed ionic-metallic bonds and Na-Na metallic bonds. This result in a drastic GB decohesion that reduces the GB tensile strength dramatically until it approaches the strength of bulk sodium. Dense segregation of sodium forms a Na film along the GB and opens an easy channel for oxidation and corrosion along the GB, which further accelerates the intergranular embrittlement.

Original languageEnglish
Article number214109
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume85
Issue number21
DOIs
Publication statusPublished - Jun 8 2012

Fingerprint

Aluminum
Grain boundaries
grain boundaries
Sodium
sodium
aluminum
embrittlement
Embrittlement
Materials science
materials science
aluminum alloys
tensile strength
Probability density function
Aluminum alloys
corrosion
Tensile strength
Corrosion
Atoms
Oxidation
oxidation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Aluminum grain boundary decohesion by dense sodium segregation. / Zhang, Shengjun; Kontsevoi, Oleg Y.; Freeman, Arthur J; Olson, Gregory B.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 85, No. 21, 214109, 08.06.2012.

Research output: Contribution to journalArticle

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