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Influence of ordering kinetics on dendritic growth morphology

Assadi, H. and Oghabi, M. and Herlach, Dieter M. (2009) Influence of ordering kinetics on dendritic growth morphology. Acta Materialia (57), pp. 1639-1647.

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Abstract

The effect of interfacial ordering kinetics on growth morphology is examined for undercooling solidification of intermetallics. The focus is on NiAl, which has been found to solidify into completely irregular seaweed-like morphologies at growth velocities of 2 m/s. The transition from regular dendritic to seaweed growth in this material is simulated using a hybrid deterministic–probabilistic model of microstructure evolution, taking account of the interfacial kinetic effects. Modelling shows that seaweed formation in intermetallic forming systems can be attributed in part to transient entrapment of the chemical and orientational disorder at the solid/liquid interface. Both types of disorder trapping give rise to strongly preferential depression of the interfacial temperature, while orientational disorder trapping also reduces the definitiveness of crystal orientation at the interface. These effects counterbalance the role of crystallographic anisotropy in promoting growth into preferred directions, and hence lead to relatively easy breakdown of regular dendritic patterns in highly ordered materials.

Document Type:Article
Title:Influence of ordering kinetics on dendritic growth morphology
Authors:
AuthorsInstitution or Email of Authors
Assadi, H.UNSPECIFIED
Oghabi, M.UNSPECIFIED
Herlach, Dieter M.dieter.herlach@dlr.de
Date:2009
Journal or Publication Title:Acta Materialia
Refereed publication:Yes
In Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Page Range:pp. 1639-1647
Status:Published
Keywords:Dendrite growth, solidification
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W FR - Forschung unter Weltraumbedingungen (old)
DLR - Research area:Space
DLR - Program:W FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):W - Vorhaben Materialwissenschaftliche Forschung (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space
Deposited By: Ingeborg Parpart
Deposited On:24 Nov 2009 15:09
Last Modified:26 Mar 2013 13:12

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