Through exerting a steady electric field on Al-9Si binary alloy in the mushy zone and liquid phase zone above liquidus

influence of electric field on the morphology and size of the primary α-Al in solidification microstructures of aluminum alloy was investigated.Temperature data during the cooling process of Al-9Si melt was measured and collected with temperature recording instrument XJY-160

and the solidification microstructure was analyzed by OM（optical microscope） and Image pro plus software.The results show that with the increase of current density

the size of primary α grains are decreased first rapidly and then slowly under a steady electric field

and critical current density is 330 mA·mm-2.Both the Pinch effect and thermoelectric magnetohydrodynamic（TEMHD） caused by steady electric field are responsible for restraining dendirtic growth of the primary α-Al grains in the Al-9Si alloy.