Revealing the mechanisms by which magneto-hydrodynamics disrupts solidification microstructures
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
A key technique for controlling solidification microstructures is magneto-hydrodynamics (MHD), resulting from imposing a magnetic field to solidifying metals and alloys. Applications range from bulk stirring to flow control and turbulence damping via the induced Lorentz force. Over the past two decades the Lorentz force caused by the interaction of thermoelectric currents and a magnetic field, a MHD phenomenon known as Thermoelectric Magnetohydrodynamics (TEMHD), was also shown to drive inter-dendritic flow altering microstructural evolution. In this contribution, high-speed synchrotron X-ray tomography and high-performance computational simulation are coupled to reveal the evolution, dynamics and mechanisms of solidification within a magnetic field, resolving the complex interplay and competing flow effects arising from Lorentz forces of different origins. The study enabled us to reveal the mechanisms disrupting the traditional columnar dendritic solidification microstructure, ranging from an Archimedes screw-like structure, to one with a highly refined dendritic primary array. We also demonstrate that alloy composition can be tailored to increase or decrease the influence of MHD depending on the Seebeck coefficient and relative density of the primary phase and interdendritic liquid. This work paves the way towards novel computational and experimental methods of exploiting and optimising the application of MHD in solidification processes, together with the calculated design of novel alloys that utilise these forces.
Date Issued
2020-09-01
Date Acceptance
2020-06-22
Citation
Acta Materialia, 2020, 196, pp.200-209
ISSN
1359-6454
Publisher
Elsevier
Start Page
200
End Page
209
Journal / Book Title
Acta Materialia
Volume
196
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000557651000019&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Materials Science, Multidisciplinary
Metallurgy & Metallurgical Engineering
Materials Science
Magneto-hydrodynamics
Solidification microstructure
Alloys
Thermoelectric convection
TO-EQUIAXED TRANSITION
DIRECTIONAL SOLIDIFICATION
TOMOGRAPHIC QUANTIFICATION
FIELD
GROWTH
ALLOYS
FLOW
REFINEMENT
CONVECTION
METALS
Publication Status
Published
Date Publish Online
2020-06-26