On the origin of the mixed alkali effect on indentation in silicate glasses

Jonas Kjeldsen, Morten M. Smedskjaer, John Mauro, Yuanzheng Yue

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Abstract

The compositional scaling of Vickers hardness (Hv) in mixed alkali oxide glasses manifests itself as a positive deviation from linearity as a function of the network modifier/modifier ratio, with a maximum deviation at the ratio of 1:1. In this work, we investigate the link between the indentation deformation processes (elastic deformation, plastic deformation, and densification) and Hv in two mixed sodium-potassium silicate glass series. We show that the mixed alkali effect in Hv originates from the nonlinear scaling of the resistance to plastic deformation. We thus confirm a direct relation between the resistance to plastic flow and Hv in mixed modifier glasses. Furthermore, we find that the mixed alkali effect also manifests itself as a positive deviation from linearity in the compositional scaling of density for glasses with high alumina content. This trend could be linked to a compaction of the network when two types of alkali ions co-exist.

Original languageEnglish (US)
Pages (from-to)22-26
Number of pages5
JournalJournal of Non-Crystalline Solids
Volume406
DOIs
StatePublished - Dec 15 2014

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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