On the primary silicon precipitation during the eutectic solidification of Al-Si alloys

During the Al-Si eutectic alloy solidification, silicon distribution throughout the melt is not homogeneous which causes silicon segregation. A four phase Eulerian model of solidification is developed and invoked in Ansys Fluent simulation software to track the silicon segregation location and to understand the distribution of the segregating silicon in the Al-Si metal matrix. The recalescence phenomena are also observed during the solidification process. It is found that the silicon segregation is nearly 1.08 volume %, and the silicon is mostly found near the top surface of the simulation domain. It is also revealed through the numerical simulation that the columnar solid phase grains grow rapidly towards the center of the casting in the early stage of the solidification and the segregating silicon phase is generated near the columnar phase. However, the globular solid phases are also observed at the center of the simulation domain. The above numerical predictions are satisfactorily validated with the in-house experiment conducted using a specific alloy known as eutectic Al-Si (LM6).