Influence of Pulse Electric Current on Solidification Structures of Al-Si Alloys

Abstract

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 α-Al and Si were analysed.The experimental results showed that α- 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 α- 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

Hypereutectic Al-Si Alloy with Completely Nodular Eutectic Silicon: Microstructure and Process

“…But these chemical additions, either individually or complex, don't lead the morphological change from multi-faceted primary Si into spheres. The physical method involves overheating [19][20][21], electromagnetic stirring [22,23] and electric current [24,25] which greatly refine the primary Si and modify its morphology. However, expensive equipment and complex operation restrict their usage in foundry.…”

Comparative analysis of functional possibilities of methods of pulse treatment of a melt

“…The impact on the melt by pulses repeated at fre quency f is performed by immersion of the waveguide flank into the melt, whose shifting mechanical pulses are realized by means of electric charges in a special device, whose working unit is a waveguide. The PECT of the melt began to be developed in recent years [11,12,18,19]. The loading of the melt by this method is performed by the direct discharges of cur rent in the melt between the electrodes being immersed.…”

Untitled

“…Розмір, розподіл за розмірами та морфологія евтектичних частинок кремнію не змінюються під впливом електричного струму для обох стопів. 106 А. Г. БОРИСОВ, Т. Г. ЦІР В роботі [53] в процесі охолодження починаючи з температури ліквідусу (710°С), через зразок стопу Al-22Si, що твердне, кожні 20 с пропускався електричний імпульс (розрядка конденсатору, напруги розряду були 3 кВ і 6 кВ). Відзначається, що в необробленому стопі первинний кремній дуже крупний, оброблення приводило до його істотного подрібнення.…”