1987 Volume 37 Issue 3 Pages 228-238
The purification behaviors of liquid aluminiums containing impurity elements have been investigated by means of segregation process which utilizes segregation phenomena of solute in the solidification of liquid metal. After liquid aluminium was unidirectionally solidified under the conditions of ultrasonic vibration and mechanical stirring, the distribution of impurity concentration was examined against the solidified length. Copper, Magnesium and iron in liquid aluminium were used as impurity elements. The experimental results obtained are summarized as follows:
(1) For each aluminium alloy, the distribution of impurity concentration after the solidification was dependent on initial impurity concentration in liquid aluminium. These behaviors could be explained by the variation of the shape in the solid-liquid interface which is presumed by constitutional supercooled theory.
(2) When aluminium alloys containing low impurity were solidified with the conditions of ultrasonic vibration and mechanical stirring, the purification of aluminium alloys proceeded in accordance with theoretical solidified curve.
(3) The effects of ultrasonic vibration and mechanical stirring on the purification of aluminium alloys having the concentration of high impurity were larger than those of aluminium alloys containing low impurity. These results may suggest that the solid-liquid interface during the solidification is fully mixed with ultrasonic vibration and mechanical stirring and impurity elements escaped from the solid transfers easily to bulk layer in melt.
