2004 Volume 45 Issue 6 Pages 1944-1948
The static magnetic field and the alternating electric field were simultaneously imposed on the melt of Al-7%Si hypo-eutectic alloy, and primary α-dendrite particles were refined by electromagnetic vibrations imposed during solidification. The refinement mechanism of primary α-dendrite particles was quantitatively investigated in terms of vibration intensity. When the vibration intensity was increased, coarse equiaxed dendrite particles decreased, and primary α-dendrites approached a globular shape that size was about 25 μm in diameter. By contrast, dendrite arm spacing (DAS) remained intrinsically unchanged even if vibration intensity was changed with electric current intensity. Refinement of primary α-dendrite particles was likely to be caused by collapse of dendrite arms due to the micro-explosion and stirring of the melt.