Silicon crystal morphologies during solidification refining from Al-Si melts

At lower silicon contents the silicon morphologies have a fish-bone or star-like shape but as the Si content increases the morphology changes to a plate-like structure, which becomes coarser with increasing Si concentration. The growth pattern for coarse plates growing as (1 1 1) platelets tend to form pockets of aluminium, which will end up as inclusions during dissolution of the matrix.