Influence of a Slow Rotating Magnetic Field in Thermoelectric Magnetohydrodynamic Processing of Alloys

Kao, Anne; Lee, Peter; Pericleous, K.

doi:10.2355/isijinternational.54.1283

Cited by 9 publications

(1 citation statement)

References 18 publications

(17 reference statements)

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“…) and it is well known that applying a static magnetic field changes the melt flow leading to electromagnetic damping [8] or alternatively, a travelling field (including a rotating magnetic field) leads to electromagnetic stirring (EMS) [9,10]. A static magnetic field has also been seen to drive flow through its interaction with inherent thermoelectric currents [11][12][13][14], generated in solidifying alloys due to spatial variations in temperature and Seebeck coefficient [11,[15][16][17]. This thermoelectric Lorentz force ( #! )…”

Section: Introductionmentioning

confidence: 99%

Revealing the mechanisms by which magneto-hydrodynamics disrupts solidification microstructures

et al. 2020

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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 the 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 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.

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Section: Introductionmentioning

confidence: 99%

Revealing the mechanisms by which magneto-hydrodynamics disrupts solidification microstructures

et al. 2020

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Numerical Research on Magnetic Field, Temperature Field and Flow Field During Melting and Directionally Solidifying TiAl Alloys by Electromagnetic Cold Crucible

Chen

Yang

Gong

et al. 2017

Metall Mater Trans B

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4D synchrotron X-ray tomographic quantification of the transition from cellular to dendrite growth during directional solidification

et al. 2016

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Solidification morphology directly impacts the mechanical properties of materials; hence many models of the morphological evolution of dendritic structures have been formulated. However, there is a paucity of validation data for directional solidification models, especially the direct observations of metallic alloys, both for cellular and dendritic structures. In this study, we performed 4D synchrotron X-ray tomographic imaging (three spatial directions plus time), to study the transition from cellular to a columnar dendritic morphology and the subsequent growth of columnar dendrite in a temperature gradient stage. The cellular morphology was found to be highly complex, with frequent lateral bridging. Protrusions growing out of the cellular front with the onset of morphological instabilities were captured, together with the subsequent development of these protrusions into established dendrites. Other mechanisms affecting the solidification microstructure, including dendrite fragmentation/pinch-off were also captured and the quantitative results were compared to proposed mechanisms. The results demonstrate that 4D imaging can provide new data to both inform and validate solidification models

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Influence of a Slow Rotating Magnetic Field in Thermoelectric Magnetohydrodynamic Processing of Alloys

Cited by 9 publications

References 18 publications

Revealing the mechanisms by which magneto-hydrodynamics disrupts solidification microstructures

Revealing the mechanisms by which magneto-hydrodynamics disrupts solidification microstructures

Numerical Research on Magnetic Field, Temperature Field and Flow Field During Melting and Directionally Solidifying TiAl Alloys by Electromagnetic Cold Crucible

4D synchrotron X-ray tomographic quantification of the transition from cellular to dendrite growth during directional solidification

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