Direct Observation of the Crystallization of Li ₂ O‐Al ₂ O ₃ ‐SiO ₂ Glasses Containing TiO ₂

Abstract

The nucleation and crystallization of Li 2 O‐Al 2 O 3 ‐SiO 2 glasses containing TiO 2 were investigated using transmission electron microscopy of thin sections produced from bulk samples. Phase separation occurs during cooling from the melt, and on heating, a large number of titanium‐aluminum crystals approximately 50 A in diameter are formed. These crystals are the heterogeneous nuclei for the crystallization of the remaining glass. Photomicrographs of various stages of crystallization show the development of the fine‐grained glass‐ceramic.