IRON ALUMINA INTERFACE IN CERAMIC MATRIX NANOCOMPOSITES

The composite powders investigated in the present study consisted of nanometric iron particles dispersed in an alumina matrix. According to the temperature of formation, iron particles are either directly epitaxied in the alumina matrix or separated from the alumina by a thin layer of iron aluminate spinel. This layer disappears after annealing under hydrogen. Transmission electron micrographic and electron microdiffraction pattern analyses led to a general epitaxial relationship between iron nanoparticles and alumina, which holds whatever the elaboration process. A mechanism for the crystallographical reorientation of the iron particles, when the spinel phase is reduced, is proposed.