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Titolo:
Undercooling and glass formation in Al-based alloys
Autore:
Das, SK; Perepezko, JH; Wu, RI; Wilde, G;
Indirizzi:
Honeywell Int Inc, Morristown, NJ 07962 USA Honeywell Int Inc Morristown NJ USA 07962 t Inc, Morristown, NJ 07962 USA Univ Wisconsin, Dept Mat Sci & Engn, Madison, WI 53706 USA Univ WisconsinMadison WI USA 53706 Mat Sci & Engn, Madison, WI 53706 USA Forschungszentrum Karlsruhe, INT, D-76021 Karlsruhe, Germany Forschungszentrum Karlsruhe Karlsruhe Germany D-76021 Karlsruhe, Germany
Titolo Testata:
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
, volume: 304, anno: 2001,
pagine: 159 - 165
SICI:
0921-5093(20010531)304:<159:UAGFIA>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMORPHOUS-ALLOYS; METALLIC GLASSES; RAPID SOLIDIFICATION; ALUMINUM-ALLOYS; CRYSTALLIZATION; MICROSTRUCTURE; KINETICS; MELTS;
Keywords:
undercooling; Al-alloys; nucleation; dispersoids; nanocrystal; amorphous phases;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Das, SK Honeywell Int Inc, 101 Columbia Rd, Morristown, NJ 07962 USA Honeywell Int Inc 101 Columbia Rd Morristown NJ USA 07962 7962 USA
Citazione:
S.K. Das et al., "Undercooling and glass formation in Al-based alloys", MAT SCI E A, 304, 2001, pp. 159-165

Abstract

In most solidification reactions, undercooled melts develop prior to the onset of crystallization. For Al-based systems, the development of undercooling at low levels is often recognized by the formation of metastable intermetallic phases. The control of the type and distribution of the intermetallics is; of importance in commercial applications. Examples of such microstructural control in Al-Fe-V-Si alloys are discussed. At increased solidification rates that are facilitated by high undercooling and effective heat flow, other opportunities fur microstructure control become available, In systems with eutectic reactions such as Al-Si, Al-Ni and Al-Fe, the asymmetric coupled zone affords the option to alter the primary phase and to produce unique fine-scale distributions of phase assemblies. Similarly, nanoscale microstructures are accessible either through direct formation during rapid solidification or in a more controlled manner through the annealing of precursor products such as supersaturated solid solutions or amorphous phases. The general classes of nanoscale microstructures include nanocrystalline intermetallic phases in an Al matrix and nanocrystalline Al in an amorphous matrix and offer outstanding mechanical property advantages. The increasing diversity of microstructural options presents important opportunities and challenges to the modeling and analysis of rapid solidification processes. Inthis effort, the fundamental information on undercooling behavior that hasbeen obtained through systematic studies of droplet solidification behavior has provided an essential guidance in modeling the potency and distribution of effective catalytic sites during nucleation. For the amorphous Al-based systems, the high undercooling for glass formation appears to be controlled largely by the suppression of growth of nuclei formed during rapid melt-quenching. A key issue in the controlled synthesis of nanocrystalline Al microstructures is the capability to control the nucleation density which appears to be Linked to quenched-in, pre-existing clusters. Recent evidence based upon amorphization during solid state mechanical alloying has providedinsight into the origin of the nanocrystalline Al dispersions and has demonstrated new possibilities for the synthesis of fully amorphous bulk Al-based glasses. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 14/07/20 alle ore 12:57:39