Search

In this minireview, we summarize experimental and numerical studies particularly concerned with applications of rotating magnetic fields (RMF) or travelling magnetic fields (TMF) to directional solidification of metal alloys. After introducing some fundamentals of electromagnetic stirring, we review the insights gained into flow-induced modifications of microstructure and the formation of freckles and macrosegregations. We further discuss recent strategies, using time-modulated RMF and TMF, which aim to overcome the deficiencies of conventional stirring, in particular flow-induced macrosegregation, by effectively controlling the flow field. On the microscale, we show that time-varying flows are able to alter the sidebranch characteristics vital to the potential of fragmentation.

We study the flow during the radial solidification of an Al-7wt pct Si melt inside a cylindrical cavity with cooled side walls which is placed in a rotating magnetic field (RMF). The solidification process is simulated by means of a continuum model which is implemented in a code which solves the axisymmetric Navier-Stokes equations. qwe first analyz the start-up of the buoyancy-driven convection driven by the radial heat flux in absence of the RMF. We show that the initial large vortex breaks up into three smaller ones. The resulting radial temperature profiles are compared with experimental data. Second, we study how the vortex structure is modified by the application of small RMF's.

Oscillatory flow instabilities in a liquid metal cylinder with a free upper surface, exposed to a rotating magnetic field (RMF), are analysed by numerical simulations of the axisymmetric Navier-Stokes equations. The critical Taylor number designating the onset of the oscillatory flow regime decreases with increasing aspect ratio A= H/R while the Taylor-number interval, where the flow oscillations occur, becomes narrower. The instability is initiated near the free surface, where an oscillatory variation of the size and position of the upper vortex in the secondary flow can be observed accompanied by a horizontal oscillation of the azimuthal velocity maximum at the free surface. The predicted flow regimes have been observed in corresponding model experiments with GaInSn using the Ultrasound Doppler Velocimetry (UDV) for flow field measurements. The occurrence of the oscillatory flow regime depends sensitively on the cleanliness of the liquid metal surface.

The effect of uniform magnetic fields on hydrogen evolution reaction during metal deposition and water electrolysis was investigated by means of electrochemical techniques coupled with in-situ microscopic observation, velocity measurements and numeric simulation. The desorption of hydrogen bubbles is enhanced in applied magnetic fields independent on their orientation relative to electrode surface. The origin of this effect is attributed to Lorentz force driven convection generated by the applied magnetic field.

Rotating magnetic fields (RMF’s) are meanwhile widely used in metallurgy. The RMF eliminates flow asymmetries and allows for the control of heat and mass transfer, and hence of the evolving microstructure during solidification processes. In an extension of previous works, devoted to the unidirectional solidification in both constant and temporarily modulated RMF’s, we now analyze the solidification driven by a radial heat flux. The model geometry is a cylinder filled with a binary aluminum-silicon alloy. The outer walls of the cylinder are held on a constant temperature of 20°C while its lower surface is adiabatic. The top surface of the alloy is free. The numerical simulations employ a hybrid solidification model which is implemented into a 2D Navier-Stokes solver based on the SIMPLE algorithm. We first re-investigate the spin-up problem, given by the simultaneous start of both cooling and acceleration of the melt, for different thermal conditions. Second, we compare the numerical results with corresponding experiments in the same model geometry which have been performed at the Helmholtz-Zentrum HZDR.

The effect of a uniform magnetic field on the hydrogen evolution reaction (HER) during water electrolysis in 0.1 M Na2SO4 solution was investigated. Irrespective of the magnetic field orientation with respect to the electrode surface, the desorption of hydrogen is enhanced by the presence of the magnetic field. This effect is displayed by a reduction of the mean bubble size as well as a narrower bubble size distribution in a magnetic field. Moreover, it is shown that in the presence of an external magnetic field the fractional bubble coverage is strongly retarded. As a consequence the current density is increased since more active sitesare available for the reduction processes. These effects are discussed with respect to the Lorentz force driven convection induced by a magnetic field. In order to resolve further the influence of a magnetic field applied in the perpendicular-to-electrode configuration, where the bulk Lorentz force is negligible, a numerical study has been performed. This revealed the mechanism of the improved desorption of a hydrogen bubble from the electrode surface. The numerical study has been validated by a model experiment. Most importantly, it is clearly demonstrated that a magnetic field superposed during water decomposition is a very effective method to intensify hydrogen evolution processes, and it should be possible to significantly improve the energetic efficiency of the hydrogen production via water electrolysis in a magnetic field.

Die Erfindung betrifft ein Verfahren und eine Einrichtung zum elektromagnetischen Rühren von elektrisch leitenden Flüssigkeiten (2,21,22) im flüssigen Zustand und/oder im Zustand des Beginns der Erstarrung der Flüssigkeit (2,21,22) unter Verwendung eines in der horizontalen Ebene eine Lorentzkraft (FL) erzeugenden, rotierenden Magnetfeldes. Die Aufgabe besteht darin, dass eine intensive dreidimensionale Strömung im In-nern der Flüssigkeit zum Durchmischen im flüssigen Zustand bis in die unmittelbare Umgebung von Erstarrungsfronten erreicht und gleichzeitig eine ungestörte, freie Oberfläche der Flüssigkeit gewährleistet werden. ...

This paper considers the directional solidification of Al-Si alloys from a water cooled copper chill. Melt stirring during solidification has been realised by utilising time-modulated AC magnetic fields in two different variants: (1) an RMF applied in form of a pulse sequence with a periodic inversion of the direction of rotation between two consecutive pulses and (2) a combination of rotating (RMF) and travelling magnetic fields (TMF), whereas both fields are implemented subsequently in form of rectangular pulses. Our results demonstrate that the melt agitation using modulated magnetic fields offers a considerable potential for a well-aimed modification of casting properties by an effective control of the flow field, but, this goal requires an optimisation of the magnetic field onfiguration with respect to the particular solidification parameters.

The application of an RMF during the solidification of a metal alloy may cause macrosegregations, which are the result of the secondary flow in the form of a double vortex structure appearing in a rotating flow due to the Ekman pumping effect. The aim of this work is to improve the understanding of the influence of turbulent RMF-driven flows on the final macrosegregation during unidirectional columnar and equiaxed solidification of a binary metal alloy. The weakly turbulent flow was modeled by means of direct numerical simulations in an axisymmetric approach, where the transient heat and mass transfer was simulated by means of a standard mixture model. Both types of solidification, columnar and equiaxed, were considered by the application of both a permeability and a hybrid model to treat the fluid flow in the mushy zone. Our analysis shows that the oscillations of the radial flow are damped by the rather high viscosity of the slurry region formed by the mixture of equiaxed dendrites and interdendritic liquid. The transport of the equiaxed dendrites towards the axis of the cylinder results in a faster cooling of the melt and a convex shape of the mushy zone. The final macrosegregation is significantly smaller in comparison with the columnar solidification. An increase of the Taylor number leads to a further decrease of the macrosegregation in the middle of the sample for two reasons. First, the enhancement of turbulent mixing of the rejected solute and floating dendrites with the bulk liquid mediated by the T-G vortices, and second, the transport of floating dendrites by the flow reduces the ‘washing’ effect, given by the convective transport of the rejected solute from the solid interface, in comparison with non-movable dendrites.

The paper presents a study concerning the impact of a turbulent, rotating melt flow on the macrosegregation and the shape of the mushy zone during unidirectional solidification of an Al-7wt%Si alloy. The flow is generated by applying a rotating magnetic field (RMF). Direct numerical simulations (DNS) were performed to study the weakly turbulent flow. The transient heat and mass transfer were simulated using a standard mixture model (Bennon and Incropera, 1987). The treatment of the fluid flow in the mushy zone requires the use of permeability and mixture viscosity models, which also allow for consideration of both columnar and equiaxed solidification. Our results demonstrate that in the case of columnar solidification the Ekman pumping effect causes the development of a Si-enriched liquid channel along the rotational axis . The Taylor-Goertler vortices, which appear randomly along the side wall of the cylinder, amplify the solute transport from the wall to the axis intermittently in the upper part of the mushy zone. This effect leads to a wavy shape of the mushy zone and segregation in the form of a fir tree with a distinct accumulation of silicon along the axis of the cylinder. Moreover, we propose strategies to avoid macrosegregation by using a pulse-modulated rotating magnetic field.

In dieser Arbeit wird die Wirkung des elektromagnetischen Rührens der Restschmelze bei der gerichteten Erstarrung einer Al-Si-Legierung untersucht. Dabei wird eine neue Methode zum elektromagnetischen Rühren unter Nutzung eines rotierenden Magnetfeldes (RMF) und eines wandernden Magnetfeldes (TMF) vorgeschlagen, bei der beide Felder einzeln aufeinanderfolgend in Form von Rechteckpulsen angewandt werden. Beim konventionellen elektromagnetischen Rühren mit kontinuierlich wirkenden Feldern treten oft strömungsinduzierte Entmischungen im Gefüge auf. Mit der Strategie der Nutzung zeitmodulierter Felder sollen diese bekannten Nachteile vermieden werden. Die Ergebnisse zeigen, dass das Rühren unter Anwendung eines modulierten magnetischen Feldes Möglichkeiten zur Beeinflussung des Erstarrungsgefüges durch eine effiziente Kontrolle des Strömungsfeldes vor der Erstarrungsfront bietet. Eine erfolgreiche Anwendung erfordert eine dem jeweiligen Prozess angepasste Optimierung der Magnetfeldparameter.

The rotary stirring during solidification has been proved to be a striking method for achieving a purposeful alteration of the microstructure of casting ingots, such as grain refinement or the promotion of a transition from a columnar to an equiaxed dendritic growth (CET). However, the imposition of a rotating magnetic field (RMF) also causes problems like the occurrence of typical segregation pattern or a deflection of the upper free surface leading to surface defects or the entrainment of gas. A permanent radial inward flow along the solidification front is responsible for the transport of solute to the axis of the ingot resulting in typical freckle segregation pattern in form of vertical channels filled with alloy of eutectic composition. We present a new innovative method of electromagnetic stirring using a modulated RMF which offers a considerable potential for a well-aimed modification of casting properties. This paper considers the directional solidification of Al-Si alloys from a water cooled copper chill. Modulated AC magnetic fields were applied for melt agitation. The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results demonstrate that the modulated magnetic field enables an effective control of the flow field and the structure of the solidified samples.

Die Erfindung betrifft ein Verfahren und eine Einrichtung zum elektromagneti-schen Rühren elektrisch leitfähiger Flüssigkeiten (2) unter Verwendung eines in der horizontalen Ebene rotierenden Magnetfeldes RMF (34) und eines dazu in vertikaler Richtung wandernden Magnetfeldes WMF (47). Die Aufgabe besteht darin, dass unsymmetrische Strömungsstrukturen in mit Schmelzen gefüllten Behältern, insbesondere zu Beginn und während des Ver-laufs der Erstarrung vermieden werden. Außerdem sollen eine effektive Durch-mischung der Flüssigkeit und/oder eine kontrollierte Erstarrung metallischer Le-gierungen unter Vermeidung der Ausbildung von Entmischungszonen im Erstar-rungsgefüge erreicht werden. Die Lösung besteht darin, dass sowohl das rotierende Magnetfeld RMF (34) als auch das wandernde Magnetfeld WMF (47) diskontinuierlich in Form von zeitlich begrenzten und einstellbaren Periodendauern (TP,RMF,TP,WMF) und abwechselnd zeitlich nacheinander über zugehörige Induktionsspulen (31,32,33;41,42,43,44, 45,46) zugeschaltet werden.

Alternating current (AC) magnetic fields are commonly used in industrial practice for melt stirring. The requirements arising from the particular metallurgical or casting operation can be manifold. For instance, the electromagnetic stirring is applied to provide an efficient mixing of metallic melts, to control the flow at the mold region in the continuous casting process or to achieve a purposeful alteration of the microstructure of casting ingots. In the present study we introduce a novel type of electromagnetic stirring using a pulse-modulated rotating magnetic field (RMF). Capabilities of this approach are exemplarily demonstrated for controlling the melt flow during the unidirectional solidification of an Al-7wt%Si alloy. Two variants have been examined. Firstly, we use a succession of pulses that always have the same rotational direction (RMF-PSCD). Secondly, we use an RMF pulse sequence of alternating direction (RMF-PSAD). The latter method is related to a periodic inversion of the sense of rotation between two consecutive pulses. The characteristic period of the inversion for RMF-PSAD and of the pulses for RMF-PSCD is derivable from the spin-up dynamics of a continuously applied RMF. Numerical and experimental investigations of different configurations applying an RMF either continuously or in form of RMF-PSAD and RMF-PSCD reveal the development of different flow pattern. It was found that the application the time-modulated RMF with suitable modulation frequencies delivers a homogeneous, equiaxed microstructure. Typical segregation pattern or flow-induced gas porosity usually arising from a continuous RMF application can be avoided with the new stirring methods. Essential features of the interplay between the electromagnetically-driven melt flow and solidification parameters such as temperature and mixture mass concentration of Si are discussed. Our results demonstrate that the success of the presented RMF-PSAD technique requires a precise tuning of the magn

AC magnetic fields are used in industrial practice for melt stirring. The requirements are manifold for miscellaneous metallurgical operations or casting technologies, mainly the magnetic field application should provide an efficient mixing of the melt in order to achieve homogeneous distributions of solute and/or temperature. The rotary stirring during solidification has been proved to be a striking method to achieve a purposeful alteration of the microstructure of casting ingots, such as a distinct grain refining or the promotion of a transition from a columnar to an equiaxed dendritic growth (CET). Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Al-Si alloys from a water cooled copper chill. A modulated rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure the temperature field during solidification. The velocity field in the liquid phase was determined by means of Ultrasound Doppler velocimetry (UDV). The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results demonstrate that the modulated magnetic field enables an effective control of the flow field and the structure of the solidified samples.

The rotary stirring during solidification has been proved to be a striking method for achieving a purposeful alteration of the microstructure of casting ingots, such as grain refinement or the promotion of a transition from a columnar to an equiaxed dendritic growth (CET). However, the imposition of a rotating magnetic field (RMF) also causes problems like the occurrence of typical segregation pattern or a deflection of the upper free surface leading to surface defects or the entrainment of gas. A permanent radial inward flow along the solidification front is responsible for the transport of solute to the axis of the ingot resulting in typical freckle segregation pattern in form of vertical channels filled with alloy of eutectic composition. We present a new innovative method of electromagnetic stirring using a modulated RMF which offers a considerable potential for a well-aimed modification of casting properties. This paper considers the directional solidification of Al-Si alloys from a water cooled copper chill. Modulated AC magnetic fields were applied for melt agitation. The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results demonstrate that the modulated magnetic field enables an effective control of the flow field and the structure of the solidified samples.

The present study considers the solidification of an Al-7wt%Si alloy under the influence of electromagnetic melt stirring using a rotating magnetic field (RMF). The effect of a continuously applied RMF is compared with an RMF pulse sequence of alternating direction (RMF-PSAD). The resulting flow structure in a cylindrical liquid metal column has been measured by isothermal experiments using the ternary alloy GaInSn. The solidification experiments performed with the Al-7wt%Si alloy confirm our numerical predictions concerning the temperature field during solidification and the distribution of primary crystals and eutectic phase in the solidified samples. The application of the RMF-PSAD regime at suitable frequencies of the reversals of the magnetic field direction fP delivers an equiaxed microstructure without macrosegregation.

This paper presents a study concerning the transient dynamics of the flow field inside a liquid metal column created by an application of a rotating magnetic field (RMF) in form of a single pulse. The flow structure is governde by an impulsive spin-up form the rest state which is followed by a spin-down phase under the inertia of the fluid. A distinctive influence of pulse length the transient fluid flow has been found. Our results reveal that the recirculating flow in the radial-meridional plane shows periodic reversals. This phenomena is especially pronounced if the pulse length of the electromagnetic forcing corresponds to the so-called initial adjustment phase.

The paper presents a study concerning the impact of a turbulent, rotating melt flow on the macrosegregation and the shape of the mushy zone during unidirectional solidification of an Al-7wt%Si alloy. The flow is generated by applying a rotating magnetic field (RMF). Direct numerical simulations (DNS) were performed to study the weakly turbulent flow. The transient heat and mass transfer were simulated using a standard mixture model (Bennon and Incropera, 1987). The treatment of the fluid flow in the mushy zone requires the use of permeability and mixture viscosity models, which also allow for consideration of both columnar and equiaxed solidification. Our results demonstrate that in the case of columnar solidification the Ekman pumping effect causes the development of a Si-enriched liquid channel along the rotational axis . The Taylor-Goertler vortices, which appear randomly along the side wall of the cylinder, amplify the solute transport from the wall to the axis intermittently in the upper part of the mushy zone. This effect leads to a wavy shape of the mushy zone and segregation in the form of a fir tree with a distinct accumulation of silicon along the axis of the cylinder. Moreover, we propose strategies to avoid macrosegregation by using a pulse-modulated rotating magnetic field.

AC magnetic fields are used in industrial practice for melt stirring. The requirements are manifold for miscellaneous metallurgical operations or casting technologies, mainly the magnetic field application should provide an efficient mixing of the melt in order to achieve homogeneous distributions of solute and/or temperature. Applications of different magnetic fields (rotating, traveling, pulsating and combinations thereof) are connected with the occurrence of a more or less symptomatic flow pattern. Various forms of electromagnetic stirring have been studied in our laboratory. Here we consider exclusively the use of a rotating magnetic field (RMF), which has already become widespread in industrial practice. For instance, the rotary stirring during solidification has been proved to be a striking method in order to achieve a purposeful alteration of the microstructure of casting ingots, such as a distinct grain refining or the promotion of a transition from a columnar to an equiaxed dendritic growth (CET). However, the imposition of an RMF on a metal column also causes problems like the occurrence of typical segregation pattern or a deflection of the upper free surface leading to surface defects or the entrainment of gas. The RMF application provides a permanent radial inward flow along the solidification front. Such flow is responsible for the transport of solute to the axis of the ingot resulting in typical freckle segregation pattern in form of vertical channels filled with alloy of eutectic composition. In this paper we present a new innovative method of electromagnetic stirring using a modulated RMF which offers a considerable potential for a well-aimed modification of casting properties Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb Sn alloys from a water-cooled copper chill. A modulated rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure

The imposition of an RMF on a solidifying metal column causes problems like the occurrence of typical segregation pattern or a deflection of the upper free surface leading to surface defects or the entrainment of gas. The RMF application provides a permanent radial inward flow along the solidification front. Such flow is responsible for the transport of solute to the axis of the ingot resulting in typical freckle segregation pattern in form of vertical channels filled with alloy of eutectic composition. In this paper we present a new innovative method of electromagnetic stirring using a modulated RMF which offers a considerable potential for a well-aimed modification of casting properties Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb Sn alloys from a water cooled copper chill. A modulated rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure the temperature field during solidification. The velocity field in the liquid phase was determined by means of Ultrasound Doppler velocimetry (UDV). Our numerical model is based on the classical mixture formulation. The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results demonstrate the modulation magnetic field enables an effective control of the flow field and the structure of the solidified samples. Modifications of the grain structure and macrosegregation effects are discussed with respect to the details of the flow field.

Model experiments with low melting point liquid metals become an important tool to investigate the flow structure and related transport processes in melt flows being relevant for metallurgical applications. This approach is encouraged by recent developments of appropriate flow measuring techniques in the temperature range until about 300°C. The ultrasound Doppler velocimetry (UDV) which delivers instantaneous profiles of the local velocity along the ultrasonic beam is a very attractive technique to attain experimental data from flows of opaque liquids. AC magnetic fields are used in industrial practice for melt stirring. The requirements are manifold for miscellaneous metallurgical operations or casting technologies, mainly the magnetic field application should provide an efficient mixing of the melt in order to achieve homogeneous distributions of solute and/or temperature. Here the standard case of electromagnetic stirring by means of a rotating magnetic field (RMF) is considered. Especially, we study the melt flow excited by an application of an intermittently or alternately applied RMF.

The utilization of a pulsed rotating magnetic field (RMF) is presented as an auspicious method to obtain an intensive stirring and mixing in a pool of liquid metal. The RMF pulses within a sequence have been applied with constant or alternating direction, respectively. The resulting flow structure in a cylindrical liquid metal column has been explored by numerical simulations and by model experiments using the ternary alloy GaInSn. The ultrasonic Doppler velocimetry (UDV) has been used to determine profiles of the vertical velocity. The numerical results as well as the velocity measurements demonstrate the capability of the proposed stirring regimes to overcome the limited mixing character of conventional rotary stirring. The application of a time-modulated RMF offers a considerable potential to provide optimal flow pattern in a solidifying melt for reasons of a well-aimed modification of casting properties.

The application of time varying magnetic fields can be considered as an effective tool to organize a well-defined flow structure in the liquid phase affecting the nucleation and solidification parameters. Once a flow occurs in the liquid melt during solidification, nucleation and grain growth are mainly governed by the convective transport of heat and solute. The consequences on the structure of solidified ingots are widely discussed in the literature. So it is known, that the application of mechanical or electromagnetic stirring promotes the formation of fine, equiaxed grains [1-4]. Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb Sn alloys from a water cooled copper chill. A rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure the temperature field during solidification. Profiles of the velocity in the liquid phase were determined by means of Ultrasound Doppler velocimetry (UDV) [5]. Numerical simulations are based on the classical mixture formulation [6]. To calculate the viscosity in the mushy region the model proposed by Roplekar and Dantzig [7] was implemented into the code. The amplitude of the electric currents induced by the RMF are altered if the electrical conductivity of the growing solid phase deviates from that of the liquid phase. Previous investigations [8] showed that for such a situation numerical predictions of the velocity field using a stationary Lorentz force term become questionable. For our calculations presented here the Lorentz force term has been recalculated for each time step. The comparison between numerical simulations and solidification experiments delivered a good agreement. Due to the permanent changes both of the aspect ratio of the fluid volume and the material properties during solidification the flow field shows a transient behaviour being more complex as known from the stationary, isothermal case. Our results

Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb Sn alloys from a water cooled copper chill. A rotating magnetic field (RMF) was applied for melt agitation. The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results disclose that the forced convection causes distinct modifications of the temperature and concentration field. The electromagnetic stirring promotes the columnar-to-equiaxed transition and causes a considerable grain refinement. Indications for a flow-induced fragmentation have been found in the microstructure of the stirred samples.

Es werden Instabilitäten gedämpft und das Kornwachstum während der Erstarrung von Legierungen gesteuert.

An important factor to influence the microstructure of a metallic alloy is the convection in the melt during the solidification process. The application of time varying magnetic fields can be considered as an effective tool to organise a well-defined flow structure in the liquid phase affecting the nucleation and growth process. The aim of our work is to improve the understanding of the basic mechanisms allowing us to find a strategy to refine the microstructure of castings by an optimal combination of magnetic field intensity, field frequency and cooling rate. Directional solidification experiments were carried out with a Pb85wt%Sn alloy contained inside a cylindrical crucible with a diameter of 50 mm. A melt height of 60 mm was chosen. The container bottom is positioned on a water cooled copper chill allowing a directed solidification by a vertical heat flux. A rotating magnetic field was generated by an inductor system with 6 coils. A maximum field amplitude up to 25 mT can be applied. The frequency of the field can be varied between 10 and 400 Hz. Local temperatures were determined during the solidification process using a set of thermocouples. Cooling curves measured at different locations inside the sample reveal the significant influence of the electromagnetic convection on the local heat transfer. Profiles of the melt velocity were obtained applying the ultrasonic Doppler method.. The Pb-85wt%Sn alloy shows a microstructure with primary tin-crystallites and eutectic. Specimens solidified without a rotating magnetic field showed a columnar dendritic microstructure which is orientated in heat flux direction. The tin crystallites and the eutectic are homogeneously distributed over the whole sample. If the alloy solidifies in a rotating magnetic field the microstructure changes. The shape of the dendrites changes from columnar to equiaxed in direction from the bottom to the top of the specimen and in the same direction the volume content of the eutectic increase

The aim of this work is to predict the influence of the external magnetic field on the solidification process of two-component material. Based on the continuum model of two-phase flow a mathematical model for the directional solidification of a binary alloy in an applied magnetic field is presented. The model includes mass, momentum, energy and species conservation equations and additional relationships describing the temperature-solute coupling. The geometry under study is a cylindrical mold with adiabatic walls and cooled bottom. The macroscale transport in the solidification of alloys is governed by the progress of the two-phase mushy zone which is treated by means of a porous medium approach. The results of calculation are compared with experimental data. The experiments as well as the calculations showed that by rotation of the liquid phase caused by the Lorentz force, the solidifcation front has a non-linear surface.