Prediction of thermal cross-slip stress in magnesium alloys from a geometric interaction model

Joseph A. Yasi, Louis G. Hector, Dallas R. Trinkle

Research output: Contribution to journalArticle

Abstract

We develop a geometry-based model from first-principles data for the interaction of solutes with a prismatic screw dislocation core, and predict the thermally activated cross-slip stress above room temperature in Mg alloys. Electronic structure methods provide data for the change in prismatic stacking fault energy for different possible fault configurations for 29 different solutes. The direct solute-dislocation interaction energies for solutes that produce stable prismatic screw dislocation cores (K, Na, Sc and Ca) is correlated with stacking fault misfits. This geometric interaction model produces similar prediction errors for all 29 solutes. The model predicts alloys with cross-slip stresses lower than pure Mg for three previously considered solutes (K, Na and Sc) and three new solutes (Ca, Y and Zr). The model also qualitatively confirms the experimental observation that Mg-Li alloys have lower cross-slip stress than pure Mg. In particular, low concentrations of Y are predicted to significantly decrease the cross-slip stress in Mg.

Original languageEnglish (US)
Pages (from-to)2350-2358
Number of pages9
JournalActa Materialia
Volume60
Issue number5
DOIs
StatePublished - Mar 1 2012

Keywords

  • Cross-slip
  • Density functional theory
  • Dislocations
  • Magnesium alloys
  • Plastic deformation

ASJC Scopus subject areas

  • Ceramics and Composites
  • Metals and Alloys
  • Polymers and Plastics
  • Electronic, Optical and Magnetic Materials

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