The critical cooling rates required to form glass have been measured for Na2OSiO2 compositions containing 15.4, 20.6, 29.9 and 34.0 wt% Na2O and for K2OSiO2 compositions containing 15.3, 21.7, 34.3, 41.8 and 43.9 wt% K2O. Pronounced minima in critical cooling rate are observed in the ranges about 25 wt% Na2O and 33 wt% K2O. The locations of these minima correlate with regions of low liquidus temperatures (near eutectics) in the phase diagrams. Calculations of critical cooling rates have been carried out using the analysis of crystallization statistics and the simplified model of glass formation. In both cases, the models predict well the measured critical cooling rates and their variation with composition.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry