Atomistic insights into dislocation-based mechanisms of void growth and coalescence

Changwen Mi, Daniel Buttry, Pradeep Sharma, Demitris A. Kouris

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

One of the low-temperature failure mechanisms in ductile metallic alloys is the growth of voids and their coalescence. In the present work we attempt to obtain atomistic insights into the mechanisms underpinning cavitation in a representative metal, namely Aluminum. Often the pre-existing voids in metallic alloys such as Al have complex shapes (e.g. corrosion pits) and the defromation/damage mechanisms exhibit a rich size-dependent behavior across various material length scales. We focus on these two issues in this paper through large-scale calculations on specimens of sizes ranging from 18 thousand to 1.08 million atoms. In addition to the elucidation of the dislocation propagation based void growth mechanism we highlight the observed length scale effect reflected in the effective stressstrain response, stress triaxiality and void fraction evolution. Furthermore, as expected, the conventionally used Gursons model fails to capture the observed size-effects calling for a mechanistic modification that incorporates the mechanisms observed in our (and other researchers) simulation. Finally, in our multi-void simulations, we find that, the splitting of a big void into a distribution of small ones increases the load-carrying capacity of specimens. However, no obvious dependence of the void fraction evolution on void coalescence is observed.

Original languageEnglish (US)
Pages (from-to)1858-1871
Number of pages14
JournalJournal of the Mechanics and Physics of Solids
Volume59
Issue number9
DOIs
StatePublished - Sep 1 2011

Keywords

  • Atomistic simulations
  • Crystal plasticity
  • Dislocations
  • Void cavitation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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