Effect of strontium on the kinetics of formation and segregation of intermetallic compounds in A380 aluminum alloy

Gravity segregation of intermetallic compounds in the melt of A380 aluminum alloy has been investigated in both un-modified and Sr-modified states. Sedimentation was investigated at 630 deg. C for settling times of 30, 90, and 180 min in an electrical resistance furnace. The effect of settling time and height of melt on the amount of intermetallic compounds was studied by using image analysis. Sr-modification decreases the volume percent, size and number of settled intermetallics at the floor of the melt for all holding times. Distribution of alloying elements in Sr-modified melt is, also, more homogenous than un-modified melt. Kinetics of formation and segregation of intermetallic particles at the temperature of 630 deg. C have been modeled by Avrami and Stokes' equations. It has been shown that Sr-modification delays the formation and settling of intermetallic compounds in the melt.