Effect of a Rotating Magnetic Field on the Solidified Structure of Al-Si Alloys

2006 ◽  
Vol 508 ◽  
pp. 263-268 ◽  
Author(s):  
Jenő Kovác ◽  
András Roósz ◽  
János Szőke
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Microstructure Evolution ◽  
Research Work ◽  
Unidirectional Solidification ◽  
Rotating Magnetic Field ◽  
Electromagnetic Stirring ◽  
Convective Conditions ◽  
Microstructure Formation ◽  
Secondary Dendrite Arm Spacing

The aim of our research work is to study the microstructure formation during casting of technical alloys under diffusive and magnetically controlled convective conditions on earth and in space. Unidirectional solidification experiments under steady-state conditions were performed with Al-Si binary alloys containing three different amounts of Si, using electromagnetic stirring of the melt. The influence of the rotating magnetic field on the microstructure evolution (particularly on the secondary dendrite arm spacing) as compared to experiments without stirring was studied.

Modelling of Al-7%wtSi-1wt%Fe Ternary Alloy: Application to Space Experiments with a Rotating Magnetic Field

2014 ◽  
Vol 790-791 ◽  
pp. 46-51 ◽  
Author(s):  
Olga Budenkova ◽  
Florin Baltaretu ◽  
Sonja Steinbach ◽  
Lorenz Ratke ◽  
András Roósz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Materials Science ◽  
Primary Dendrite ◽  
Space Station ◽  
Rotating Magnetic Field ◽  
Electromagnetic Stirring ◽  
International Space ◽  
Secondary Dendrite Arm Spacing ◽  
Dendrite Arm Spacing ◽  
Space Experiments

Recently several experiments on directional solidification of Al-6.5wt.Si-0.93wt.%Fe (AlSi7Fe1) alloy were performed under terrestrial conditions and onboard the International Space Station (ISS) in the Materials Science Lab (MSL) with use of electromagnetic stirring and without it. Analysis of the samples showed that stirring with a rotating magnetic field lead to the accumulation of iron-rich intermetallics in the center of the sample and influenced the primary dendrite spacing while the secondary dendrite arm spacing were not affected. In the present paper the accumulation of the intermetallics b-Al5SiFe in the center of the samples due to RMF stirring is demonstrated numerically and the evolution of primary and secondary dendrite arm spacing is discussed.

scholarly journals Microstructure formation and macroscopic dynamics of ferrofluid emulsion in rotating magnetic field

2018 ◽  
Vol 185 ◽  
pp. 09004 ◽  
Author(s):  
Anastasia Kolesnikova ◽  
Arthur Zakinyan ◽  
Yuri Dikansky
Keyword(s):  
Magnetic Field ◽  
Molecular Dynamics ◽  
Field Strength ◽  
Molecular Dynamics Simulations ◽  
Time Evolution ◽  
Formation Process ◽  
Rotating Magnetic Field ◽  
Microstructure Formation ◽  
Water Emulsion ◽  
Dynamics Simulations

The ferrofluid-in-water emulsion has been produced and studied. The microstructure formation in a flat layer of such emulsion under the action of in-plane rotating magnetic field has been observed. Several microstructure types have been found such as chain-like aggregates, disc-like clusters, branching and space-occupying structures. The time evolution of the formation process has been analysed. The revealed microstructures have been computationally investigated by molecular dynamics simulations. The microstructure dynamics in ferrofluid emulsions manifests itself in macroscopic mechanical effects. We analysed the appearance of macroscopic torque on a ferrofluid emulsion sample in a rotating magnetic field. The value of the torque has been measured as a function of magnetic field strength and frequency.

Effect of Rotating Magnetic Field on Microstructure Evolution of Pb-Bi Alloys

2011 ◽  
Vol 311-313 ◽  
pp. 600-608
Author(s):  
Zhao Chen ◽  
Xiao Li Wen ◽  
Chang Le Chen
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Microstructure Evolution ◽  
Solidification Process ◽  
Nucleation And Growth ◽  
Primary Phase ◽  
Rotating Magnetic Field ◽  
Growth Behaviour ◽  
Solidification Behaviour ◽  
40 Hz

Solidification behaviour of Pb-Bi alloys under rotating magnetic field (RMF) was investigated experimentally to understand the effect of the frequency of RMF on the nucleation and growth behaviour. It was found that, as the increase of the rotating frequency, the grains are fragmented and refined gradually until a transition from columnar to equiaxed microstructures happens at a rotating frequency of 40 Hz. Moreover, the Bi concentration of the primary phase decreases and macrosegregation is eliminated effectively with RMF. These are due to the effect of RMF on the nucleation, growth and fluid flow in the solidification process.

Steady-state solutions for the penetration of a rotating magnetic field into a plasma column

1981 ◽  
Vol 26 (3) ◽  
pp. 441-453 ◽  
Author(s):  
Ieuan R. Jones ◽  
Waheed N. Hugrass
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Plasma Column ◽  
Skin Effect ◽  
Rotation Frequency ◽  
Rotating Magnetic Field ◽  
Electron Current ◽  
Plasma Cylinder ◽  
Resistive Plasma ◽  
Steady State Solutions

The penetration of an externally applied rotating magnetic field into a plasma cylinder is examined. Steady-state solutions of an appropriate set of magneto-fluid equations show that, provided the amplitude and rotation frequency of the field are suitably chosen, the penetration is not limited by the usual classical skin effect. The enhanced penetration of the rotating field is accompanied by the generation of a unidirectional azimuthal electron current which is totally absent in a purely resistive plasma cylinder.

Unidirectional Solidification of Pb-Sn Alloys in a Rotating Magnetic Field

2014 ◽  
Vol 790-791 ◽  
pp. 408-413 ◽  
Author(s):  
Jenő Kovács ◽  
Arnold Rónaföldi ◽  
András Roósz
Keyword(s):  
Magnetic Field ◽  
Solidification Process ◽  
Unidirectional Solidification ◽  
Rotating Magnetic Field ◽  
Columnar Microstructure ◽  
Volume Percent ◽  
Movement Velocity ◽  
Image Analyser ◽  
Vertical Bridgman ◽  
The Magnetic Field

Cylindrical Pb-Sn alloy samples (diameter: 8 mm, length: 120 mm) of different compositions (30, 40 and 50 wt.% of Sn) were prepared from high pure (4N) components. The unidirectional solidification experiments have been performed according to the upward vertical Bridgman-method by using a rotating magnetic field (RMF) with a magnetic induction of 150 mT and with a frequency of 50 Hz. The sample-movement velocity was constant (0.05 mm/s) and the temperature gradient changed from 7 to 3 K/mm during the solidification process. The first half of samples was solidified without using the magnetic field and the second half was solidified by using the magnetic field. Under the influence of this strong flow induced by the magnetic field, the columnar microstructure of the first part decomposed and a characteristic "Christmas tree"- like macrosegregated structure with equiaxed Pb-dendrites was developed. The secondary dendrite arm spacing (SDAS) and the volume percent of primary Pb-phase (dendrite) were measured by an automatic image analyser on the longitudinal polished sections along the whole length of the samples. The effect of the forced melt flow on the micro-and macrostructure was studied in case of the different sample compositions.

Effect of the High Rotating Magnetic Field (min. 30 mT) on the Unidirectionally Solidified Structure of Al7Si0.6Mg Alloy

2010 ◽  
Vol 649 ◽  
pp. 263-268 ◽  
Author(s):  
Jenő Kovács ◽  
Arnold Rónaföldi ◽  
András Roósz
Keyword(s):  
Magnetic Field ◽  
Cross Sections ◽  
Interface Velocity ◽  
Unidirectional Solidification ◽  
Rotating Magnetic Field ◽  
The Other ◽  
Basic Parameters ◽  
Solidification Parameters ◽  
Solid Liquid Interface ◽  
Solid Liquid

The topic of this paper is the unidirectional solidification of ternary Al7Si0.6Mg aluminium alloy in a rotating magnetic field of 30 -150 mT and the characterisation of effect of stirring on the solidified structure. During performing the experiment-series, one of the three solidification parameters (temperature gradient, solid/liquid interface velocity and magnetic induction) was continuously changed and the other two of them was kept on a constant value. The effect of these parameters on the developed structures was analysed during the evaluation of the experimental results. Moreover, the extent of Si-macrosegregation as well as the change of the secondary dendrite arm spacing were investigated on the longitudinal and cross-sections of samples as a function of the three basic parameters.

Effect of Crucible Diameter and Wall Roughness on the Melt Flow Generated by Rotating Magnetic Field

2010 ◽  
Vol 659 ◽  
pp. 251-256
Author(s):  
Arnold Rónaföldi ◽  
Jenő Kovács ◽  
András Roósz
Keyword(s):  
Magnetic Field ◽  
Unidirectional Solidification ◽  
Rotating Magnetic Field ◽  
Wall Roughness ◽  
Melt Flow

The effect of flow on the structure of solidified alloys can be investigated by the unidirectional solidification of alloys stirred with a magnetic (magnetohydrodynamics – MHD) method. This MHD method is a rotating magnetic field (RMF)-type. The paper deals with the melt flow generated by this RMF.

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