Numéro
J. Phys. IV France
Volume 03, Numéro C7, Novembre 1993
The 3rd European Conference on Advanced Materials and Processes
Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés
Page(s) C7-1407 - C7-1412
DOI http://dx.doi.org/10.1051/jp4:19937216
The 3rd European Conference on Advanced Materials and Processes
Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés

J. Phys. IV France 03 (1993) C7-1407-C7-1412

DOI: 10.1051/jp4:19937216

Synthesis of alumina-metal nanocomposites by mechanical alloying

D. OSSO1, G. LE CAER1, S. BEGIN-COLIN1, A. MOCELLIN1 and P. MATTEAZZI2

1  LSG2M, URA 159 du CNRS, Ecole des Mines, 54042 Nancy cedex, France
2  Dipartimento di Scienze e Tecnologie Chimiche, Università degli Studi di Udine, via del Cotonificio 108, Udine, Italy


Abstract
The synthesis of nanometer-sized [MATH]-Al2O3-metal composites can be performed by room temperature ball-milling of mixtures of metal-oxides and aluminium as shown by Matteazzi and Le Caër. The average crystallite size of the alumina-metal composite so obtained is in general about 10nm. Such composites may also be prepared by direct grinding of a mixture of [MATH]-Al2O3 and of a metal or an alloy. The present work is devoted to the study of the reaction mechanisms by X-Ray diffraction and 57Fe Mössbauer spectroscopy for the [MATH]-Al2O3-Cr, [MATH]-Al2O3-Fe, [MATH]-Al2O3-(Fe-Cr) and [MATH]-Al2O3-Ti systems. Mössbauer spectroscopy shows that non-completely reduced Fe, partly in the form of Fe2+, still exists at the end of the synthesis and belongs to a ternary Al-Fe-O oxide in [MATH]-Al2O3-Fe composites although it cannot be indexed by X-Ray diffraction. The Fe2+ component is mainly associated with iron environments in or similar to those of hercynite. Species like Fe3+ in Al2O3 or in grain boundaries are observed, Fe4+ and Feo cannot be excluded. Differences are obtained by reactive milling and by direct milling the reaction products. Reactive milling of Al-TiO2 (anatase) yields [MATH]-Al2O3-Ti nanocomposites. The transient formation of a high-pressure orthorhombic form of TiO2 of the [MATH]-PbO2 type is observed.



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