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Investigation of the effect of fluid flow on microstructure evolution in Al-Si-Fe alloys: The MICAST project

Steinbach, Sonja and Ratke, Lorenz and Zimmermann, Gerhard and Sturz, L. and Roosz, A. and Kovacs, Jeno and Fautrelle, Y. and Budenkova, Olga and Lacaze, J. and Dost, S. and Grün, G.-U. and Warnken, N. and Wu, M. and Sillekens, W. (2017) Investigation of the effect of fluid flow on microstructure evolution in Al-Si-Fe alloys: The MICAST project. Brunel University. SP 17, 6th Decennial International Conference on Solidification Processing, 25th-28th July 2017, Old Windsor, GB. ISBN 1908549297.

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Abstract

In secondary Al-Si-alloys, the presence of small amounts of Fe causes the formation of Fe-intermetallic phases which have a negative effect on mechanical and physical properties of castings. To understand the interaction of fluid flow and precipitating intermetallic phases and their effect on microstructure formation, unidirectional solidification experiments have been carried out on AlSi7 and AlSi7Fe1 alloys as a function of temperature gradient, G, and growth rate, v, under diffusive and controlled fluid flow conditions in the ESA payload Materials Science Lab (MSL) onboard the ISS. A strong segregation of Fe and Si towards the sample centre under convective conditions is observed. The influence of fluid flow and intermetallic phases on the solidifying microstructure was characterized by changes of primary and secondary dendrite arm spacing. In the pure binary alloy the secondary dendrite arm spacing increases under convective conditions, clearly revealing the dramatic effects of convection on solidification kinetics. Instead of a cube root relation it is observed that the secondary arms coarsen as the square root of solidification time. In contrast to this, even small amounts of iron eliminate possible effects of flow on the secondary dendrite arm spacing. These results are explained from the viewpoint of the blocking effect of the Fe-intermetallic phases on fluid flow leading to a loss in permeability of the mushy zone and a decreased solute transfer.

Item URL in elib:https://elib.dlr.de/114076/
Document Type:Conference or Workshop Item (Speech)
Title:Investigation of the effect of fluid flow on microstructure evolution in Al-Si-Fe alloys: The MICAST project
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Steinbach, Sonjasonja.steinbach (at) dlr.deUNSPECIFIED
Ratke, LorenzLorenz.Ratke (at) dlr.deUNSPECIFIED
Zimmermann, Gerhardaccess, aachenUNSPECIFIED
Sturz, L.accessUNSPECIFIED
Roosz, A.university of miskolcUNSPECIFIED
Kovacs, Jenouniversity of miskolc, hungaryUNSPECIFIED
Fautrelle, Y.simapUNSPECIFIED
Budenkova, Olgasimap grenoble institute of technologyUNSPECIFIED
Lacaze, J.cirimat, toulouseUNSPECIFIED
Dost, S.university of victoriaUNSPECIFIED
Grün, G.-U.hydro aluminium deutschland gmbh, bonnUNSPECIFIED
Warnken, N.University of BirminghamUNSPECIFIED
Wu, M.montan universität leobenUNSPECIFIED
Sillekens, W.ESTEC, NoordwijkUNSPECIFIED
Date:1 July 2017
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:pp. 267-271
Editors:
EditorsEmailEditor's ORCID iD
Fan, ZhongyunBCASTUNSPECIFIED
Publisher:Brunel University
ISBN:1908549297
Status:Published
Keywords:Dendrite Spacing; Fluid flow; Al-Si alloys; Permeability
Event Title:SP 17, 6th Decennial International Conference on Solidification Processing
Event Location:Old Windsor, GB
Event Type:international Conference
Event Dates:25th-28th July 2017
Organizer:BCAST
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Materials Research and Microgravity (MuM)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space > Scientific Experiments MP
Deposited By: Steinbach, Dr.rer.nat. Sonja
Deposited On:18 Sep 2017 12:59
Last Modified:18 Sep 2017 12:59

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