Modification of horizontal continuous casting Al–12%Si alloy using FSM master alloy

In this paper, horizontal continuous casting Al–12%Si alloy was modified by 30% fine-grained structural material (FSM) of the same composition as the master alloy. The effect of this FSM master alloy on the morphologies and crystal defects of eutectic Si has been investigated. Results show that microstructure of eutectic Si alters from coarse needle-like to fine fibrous shape after modification. TEM observations reveal that the crystal defects such as twins and stacking faults generate in the modified eutectic Si while no obvious defects are found in the unmodified Si. Furthermore, hundreds of nanoparticles present in the modified eutectic Si along with the twins and stacking faults. Finally, we determine the composition of these nanoparticles to be Si–Si bonded nanoculsters which should be the genetic factors in terms of metal structural heredity.