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The present study considers the solidification of an Al-7 wt pct 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-7 wt pct 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 f P delivers an equiaxed microstructure without macrosegregation.

New workable aluminum-based light alloys are a key issue in current materials science. In this work, thermophysical properties (density, viscosity, and electrical conductivity) of liquid Al-4 wt pct Cu, Al-20 wt pct Cu, Al-30 wt pct Cu, and AlCu4TiMg alloys have been measured in a wide temperature range. The anomalies with respect to the concentration dependence of the electrical conductivity are explained in terms of the s-d hybridization model. A comparison with data and scaling relations available in the literature is given.

Capabilities of the X-ray attenuation contrast radioscopy were used to provide a real-time diagnostic technique of the melt flow during unidirectional solidification of a Ga-30 wt pct In alloy from the bottom, which is significantly affected by solutal convection. The solidification process was visualized using a microfocus X-ray tube. The X-ray facility provided shadow radiographs at spatial resolutions of about 10 lm at frame repetition rates of 25 Hz. The optical flow approach was used to derive information about the velocity field ahead of the solidification front and in the mushy zone from the observed displacement of the brightness patterns appearing during the X-ray image sequence. Buoyancy-driven flow patterns were found at length scales much larger than the length scales of the solidifying microstructure. A strong coupling between convection and dendritic growth became apparent via flow-induced modifications of the concentration profile in the liquid.

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