CHEMICAL SYNTHESIS AND CHARACTERIZATION OF FE0.65NI0.35-MGO NANOCOMPOSITE POWDERS

Fe0.65Ni0.35-MgO nanocomposite powders containing approximately 11 wt. % of metallic phase were prepared by selective reduction of oxide soli d solutions elaborated by thermal decomposition of mixed oxalic precur sor The reduction behavior of the oxide solid solution calcinated at 8 00 degrees C was investigated by XRD, Fe-57 Mossbauer spectroscopy and TEM. These studies have revealed that a reduction temperature of 1300 degrees C is needed to obtain a high reduction rate and to prepare al loy particles of the desired composition. The metallic alloy particles dispersed in the MgO matrix have a bimodal size distribution: the lar ger ones (average size from 50 to 90 nm) are approximately spherical a nd are located at the surface of the MgO grains; the smaller ones (ave rage size from 5 to 13 nm) are spherical or cubic and generally grow e pitaxially inside the oxide grains. (C) 1997 Acta Metallurgica Inc.