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.

Revolution Number (RPM) Measurement of Molten Alloy by Pressure Compensation Method

2010 ◽  
Vol 649 ◽  
pp. 275-280 ◽  
Author(s):  
Arnold Rónaföldi ◽  
Jenő Kovács ◽  
András Roósz
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Unidirectional Solidification ◽  
Rotating Magnetic Field ◽  
Scale Model ◽  
Melt Flow ◽  
Model Experiments ◽  
Pressure Compensation ◽  
Different Diameters ◽  
Similarity Law

The melt flow has a significant effect on the structure developing during the unidirectional solidification of alloys. This phenomenon can be experienced during the solidification of melts stirred by the rotating magnetic field (RMF)-type magnetohydrodynamic (MHD) facility as well. As it would be very difficult to measure the intensity of melt flow (e.g. its revolution number, angular velocity) during solidification, it seems to be reasonable to perform the so-called "scale model" experiments applied usually in the hydrodynamics. Using the results of these measurements, conclusions can be drawn concerning the flows during solidification by means of the similarity law of hydrodynamics. The revolution number of Ga-In alloy melt placed in the rotating magnetic field can be measured by the equipment developed for performing the "scale model" experiments. The measurements were performed in crucibles with different surface roughness using melt-cylinders with different diameters located in rotating magnetic field having different frequencies and magnetic induction.

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.

scholarly journals The Effect of Rotating Magnetic Field on the Solidified Structure of Sn-Cd Peritectic Alloys

2014 ◽  
Vol 790-791 ◽  
pp. 414-419 ◽  
Author(s):  
Mária Svéda ◽  
Anna Sycheva ◽  
Jenő Kovács ◽  
Arnold Rónaföldi ◽  
András Roósz
Keyword(s):  
Magnetic Field ◽  
Volume Fraction ◽  
Energy Dispersive Spectrometer ◽  
Rotating Magnetic Field ◽  
Image Analyzer ◽  
Melt Flow ◽  
Directionally Solidified ◽  
Peritectic Alloy ◽  
Cellular Microstructure ◽  
Commercially Important

The peritectic alloys, such as some types of steel, Ni-Al, Fe-Ni, Ti-Al, Cu-Sn, are commercially important. In contrast to other types of alloys, many unique structures (e.g. banded or island ones) can form when peritectic alloys are directionally solidified under various solidification conditions. It can be observed in the course of the directional solidification experiments performed in a rotating magnetic field (RMF) that the melt flow has a significant effect on the solidified structure of Sn-Cd alloys. This effect was investigated experimentally for the case of Sn1.6 wt% Cd peritectic alloy. For this purpose, a Bridgman-type gradient furnace was equipped with an inductor, which generates a rotating magnetic field in order to induce a flow in the melt. As a result, the forced melt flow substantially changes the solidified cellular microstructure. The cell size and the volume fraction of the primary tin phase were measured by an image analyzer on the longitudinal polished sections along the entire length of the samples. The microstructure was investigated by scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS).

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.

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