Electron Backscattered Diffraction Analysis of Eutectic Solidification in a Continuous Cast Aluminum Alloy Billet

Eutectic silicon structure was modified by fine-grained structural material as the master alloy. An investigation of the crystallographic orientations of eutectic colonies has been carried out by electron backscatter diffraction. The morphologies of eutectic silicon alter from lamellar to fibrous shape after adding 30% fine-grained structural material master alloy. The coupling relationship of eutectic colonies becomes stronger in modified aluminum-silicon alloys. Furthermore, the misorientation angles in the eutectic colony change from high angle grain boundaries (>= 15 degrees) to low angle grain boundaries (<= 5 degrees). The misorientation angles inside eutectic silicon decrease from 60 degrees to low angle grain boundaries (<= 5 degrees). The primary alpha-aluminum dendrite and neighboring eutectic aluminum have almost the same crystallographic orientation in modified aluminum-silicon alloys.