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Phases Transformations in Nanostructures and Development of Ceramics and Metallics Nanocomposites

Grant number: 96/01417-5
Support type:Research Projects - Thematic Grants
Duration: August 01, 1996 - September 30, 2000
Field of knowledge:Engineering - Materials and Metallurgical Engineering
Principal Investigator:Walter José Botta Filho
Grantee:Walter José Botta Filho
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
Associated grant(s):00/06800-9 - Nanocrystalline composites obtained by reactive milling, AR.EXT
00/01382-4 - Amorphous phase formation during spray forming of ai84y3ni8co4zr1 alloy, AR.BR
99/09066-5 - Phases formed during crystallization of amorphous ai84y9ni5co2 alloy, AR.BR
+ associated grants 99/07283-9 - Magnetic properties of Fe-6%Si alloy obtained by spray forming, AR.EXT
99/00123-6 - Zuhair A. Munir | University of California - Estados Unidos, AV.EXT
98/04619-3 - Wenming Zeng | Shanghai Institute Ceramics - China, AV.EXT
98/13025-0 - Reactivity on high-energy milling induced self-sustaining reactions, AR.EXT
98/03544-0 - Wen Kui Wang | Institute of Physics/Chinese Academy of Sciences - China, AV.EXT
97/04749-1 - Al2O3 - SiC nanocomposites from alternative processing routes, AR.EXT
97/03544-7 - Charactirization and sintering of reactinve milled powders and ceramic matrix composites, AR.EXT - associated grants
Associated scholarship(s):97/12858-5 - Study of microstructure and corrosion resistance of Fe-M-B (M = Zr, Nb, Fr) nanocrystalline alloys , BP.PD
98/02499-0 - Fabrication and corrosion resistance evaluation of amorphous Fe84Nb7B9 alloy, BP.IC

Abstract

The objective of the project is the study of phase transformations associated with different processes to obtain nanostructured materials and also, by the controll of these transformations, the development of technologically relevant ceramic and metallic nanocomposites. The transformations of interest for the controll of nanostructures include all the transformations from stable to metastable phases and the thermally activated return of these phases to the equilibrium phases, recrystallization, sintering involving different mechanisms from those observed in micrometric powders, sintering with crystallization or with simultaneous recrystallization and reaction sintering. The following processes have been used to obtain amorphous or nanocrystalline precursors: high energy ball-milling (including mechanical alloying, mechanical milling, and reactive milling), combustion synthesis and rapid solidification. Processing by high energy ball milling is used to obtain amorphous or nanometric powders of the metallic systems nb-si and al-tm (tm: transition metal)-re (re: rare-earth), and of the ceramic systems al2 o3-zr o2-m(m=metal) and al2 o3/sic. Combustion synthesis is used specifically to obtain nanometric mixtures of the system al2 o3/sic, and rapid solidification is used to produce amorphous precursors in al-tm (tm: transition metal)-re (re: rare-earth) and fe-cu-nb-si-b type alloys. Composites (produced from nanostructured precursors) and nanocomposites are obtained by compacting and sintering of ultra-fine or amorphous powders or thermal treatment for the crystallization of the amorphous ribbons. Processing of the various nanocrystalline ceramic and metallic powders involves conventional sintering, liquid-phase sintering, sintering with simultaneous crystallization or recrystallization and reaction sintering. The results should contribute to the understanding of the intrinsic mechanisms associated with the processing of nanostructured materials and with the production and characterization of composites and nanocomposites materials of different systems. (AU)