Influence of pulse electric current on solidification structures of Al-Si alloys

The effect of pulse electric current with different density on solidification structures of hypoeutectic Al-7%Si, Al-10%Si and hypereutectic Al-22%Si alloys was studied. The shape and distribution of alpha-Al and Si were analysed. The experimental results showed that alpha- Al of Al-7% Si alloy is shortened when applied a pulse electric current during the solidification, and the microstructure turns from the obvious columnar crystal into rosette. After treatment with pulse electric current, the primary Si of Al-22%Si alloy was refined obviously. When the discharge voltage was 3kV, Si tended to gather at the edge of the sample and the primary a- Al appeared in this hypereutectic alloy. When the discharge voltage was 6kV, the primary Si was refined much more and distributes uniformly. Pulse electric current treatment had no evident effect on the approximate eutectic Al-10%Si alloy. The magnetic force was analysed under pulse electric current, and the reason of the phenomenon was discussed.