Effects Of Electromagnetic Vibrations On The Solidification Microstructures Of Al-Cu And Al-Si Alloys

The simultaneous application of a stationary magnetic field and of a sinusoidal electric current of low frequency during the course of solidification of Al-Cu and Al-Si alloys forces the melts into vibrations. In this thesis, the effects of electromagnetic vibrations on the solidification microstructures of Al-Cu and Al-Si alloys are investigated. The results show that the grains have transformed from dendrite to granulation for sub-eutectic Al-Cu alloy; the electromagnetic vibration tends to increase the interlamellar spacing of Al-CuAl2 eutectic, but it begins to decrease when cavitation occurs; the electromagnetic vibration causes the dendrite of a-Al crashing, tends to increase the secondary dendrite arm spacing of a-Al,but the secondary dendrite arm spacing begins to decrease when cavitation occurs. How the electromagnetic vibration effects on the solidification microstructures of alloys depends on how it effects the melt flow and the mechanism of nucleation.