A new technique has been developed by which naturally and anodically formed aluminum oxide produced on single-crystal specimens has been studied in the electron microscope. The low-temperature amorphous oxide grown by the transport of cations was smooth at the metal-oxide interface. However, the oxide-oxygen interface exhibited topography on certain crystal orientations. A high-temperature crystalline oxide was found to grow by the transport of anions. Epitaxial growth was observed on several orientations. The anisotropy of oxide thickness which occurred at elevated temperatures is discussed. The above results are considered in terms of the structure of the metal-oxide interface.

The nucleation and crystallization of Li2O‐Al2O3‐SiO2 glasses containing TiO2 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.

No abstract

No abstract

No abstract