FACETING OF THE INTERFACE BETWEEN AL2O3 AND ANORTHITE GLASS

The {10 (1) over bar 0} and {11 (2) over bar 0} Al2O3 surfaces have be en equilibrated in contact with anorthite liquid at 1600 degrees C. Th e structure of the resulting Al2O3/glass interfaces has been character ized using transmission electron microscopy. Both interfaces were unst able in the presence of the liquid and reconstructed lo give regular a rrays of facets. The (10 (1) over bar 0) interface developed (10 (1) o ver bar 1) and ((1) over bar 012) facets while the (11 (2) over bar 0) interface developed {hh<(2h)over bar>3} facets. It is proposed that t he (10 (1) over bar 0) glass/crystal interface is thermodynamically st able, but that the (11 (2) over bar 0) interface facets due to interfa ce-step migration. The microstructure thus shows that both the crystal lography and the anisotropic interface energies are important in deter mining the wetting/dewetting behavior of glass on Al2O3. (C) 1998 Acta Metallurgica Inc.