Internal reduction of chromium-doped [alpha]-alumina
- CNRS, Meudon (France). Lab. de Physique des Materiaux
- Centre d'Etudes de Chimie Metallurgique, Vitry sur Seine (France)
- CNRS, Meudon (France). Lab. de Physique des Materiaux Centre d'Etudes de Chimie Metallurgique, Vitry sur Seine (France)
(Al,Cr)[sub 2]O[sub 3] single crystals and polycrystals were internally reduced at 1,873 K in an Al/Al[sub 2]O[sub 3] buffer for periods of time ranging from 1 to 100 h. The growth kinetics of the reduction scale were measured. The microstructure of the reduction scale was investigated by SEM and TEM. As a result of the reduction, two types of discrete chromium precipitates developed inside the alumina matrix, each one being characterized by a particular morphology and a low-energy orientation relationship with respect to the alumina matrix. In addition, larger precipitates without special orientation relationship developed along the grain boundaries and at the triple junctions of the polycrystals. In the first part of this paper, the precipitate morphology and size are described in terms of the crystallography of the interface between the two crystal structures in relation to the reduction mechanism. In the second part, the global reduction scale growth is analyzed in terms of point defect fluxes across the reduction scale.
- OSTI ID:
- 7207494
- Journal Information:
- Journal of the American Ceramic Society; (United States), Vol. 77:2; ISSN 0002-7820
- Country of Publication:
- United States
- Language:
- English
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