Employing direct and alternative electric currents at the time of casting and solidification modified grains of Al and Si. The highest wear resistance was obtained in the direct current, and for alternative current the wear resistance corresponded to the electric current. The change of polarity in the pure Al did not influence the wear resistance, but for the Al-Si alloy the highest wear resistance was obtained when the mold was connected to the positive and the molten metal to the negative pole. Direct current used in the Al-Si alloy brought about three different microstructures including the stretched clusters of Si in the electrons' direction near the negative pole, fine clusters of Si in the intermediate zones that surrounded the oval shape of α-Al, and broken Si clusters near the positive pole.

Keywords: Surface composite, Wear resistance, Electric current, Modification of micro structure

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