Decoration of Dislocations by the Precipitation of Alumina in MgO · 2.9Al2O3 Spinel

Abstract

A thermal etching technique is developed to reveal dislocations in MgO · nAl2O3 (n=2.9) single crystals decorated by Al2O3 precipitation. Large plastic deformation leads to a larger density of thermal etch pits. Also, dense arrays of pits, parallel to the traces of slip planes with a surface, are observed around a Vickers identation. The cracks developed by an indentation run selectively along the 〈100〉 directions and accompany dislocations arrayed in the possible slip planes.