FIGURE 3. Consolidation of glass microbeads by hot-pressing.
From the following article:
Bulk glasses and ultrahard nanoceramics based on alumina and rare-earth oxides
A. Rosenflanz, M. Frey, B. Endres, T. Anderson, E. Richards & C. Schardt
Nature 430, 761-764(12 August 2004)
doi:10.1038/nature02729
a, Plot of 
Td against half-time of densification, 
1/2. b, 1/2 is defined as the inflection point on the relative-density–time curve indicated by the arrows for AL, AG and AY compositions, hot-pressed at 925 °C at 34 MPa.
