Kjeldsen, Jonas2; Smedskjær, Morten Mattrup5; Mauro, J. C.7; Yue, Yuanzheng2
1 Department of Chemistry and Bioscience, The Faculty of Engineering and Science, Aalborg University, VBN2 Section of Chemistry, The Faculty of Engineering and Science, Aalborg University, VBN3 The Faculty of Engineering and Science (ENG), Aalborg University, VBN4 Inorganic Amorphous Materials, The Faculty of Engineering and Science, Aalborg University, VBN5 Oxide Glass Chemistry, The Faculty of Engineering and Science, Aalborg University, VBN6 Corning Incorporated7 Corning Incorporated
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.
Journal of Non-crystalline Solids, 2014, Vol 406, p. 22-26