Alignment and Permeability of Al-7Si Alloy Directional Solidification with the Application of a Pulsed Magnetic Field

An experiment on the directional solidification of Al-7Si alloys under the influence of a pulsed magnetic field (PMF) is performed. Maximal peak value of PMF intensity up to 0.226 T between two iron cores was generated when a capacitor bank of 120 µF capacitance with initial voltage of 1000 V was triggered to a pair of solenoids. The PMF decreases the temperature gradient ahead of the liquidus front and increases the width of the mushy zone. The convection of symmetrical vortices seems to charge the intersectional growth of primary dendrite stems and the decrease of dendrite arms spacing under a PMF with higher magnetic intensities. Using Darcy's permeability law and Lehmann's model, the order of magnitude of the interdendritic liquid flow velocities with the application of PMF is evaluated. A strong damped effect of the mushy zone in the bulk flow of the melt is revealed.

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