Phases Transformations in Nanostructures and Development of Ceramics and Metallics Nanocomposites

• Grant number: 96/01417-5
• Support Opportunities: Research Projects - Thematic Grants
• Start date: August 01, 1996
• End date: September 30, 2000
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Transformation Metallurgy
• Principal Investigator: Walter José Botta Filho
• Grantee: Walter José Botta Filho
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research 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)