The Microstructure of Al-12.7%Si Eutectic Modified with Sr

The microstructure of Al-12.7%Si eutectic with addition of 0.1%Sr has been investigated across arrange of growth rate from 30 μm/s to 2 500μm/s with the aid of TEM. It has been shown that eutectic silicon phases contain high density of twins on two or more {111} systems and twin density and behavior are dependent on the growth rate. The preferred growth axis of silicon phases is in a <211 >irection and the microstructure of silicon phase can been seen as consisting of subgrains seperated by microtwins and/or stacking faults. Eutectic aluminum phases is multicrystal. There are no preferred matching relationship between eutectic aluminum and silicon phases.