Solidification of primary Si in electromagnetically levitated Al-50%Si undercooling melts

Abstract By combination of electromagnetic levitation and copper-plate quenching, deep undercooling and non-equilibrium solidification of Al-50%Si melts were realized. Through repeatedly heating and cooling, a maximum undercooling of 310 K was reached. Several different morphologies of primary Si solidified at different undercoolings were found on the quenched surfaces. With increasing of undercooling, the primary Si crystals solidified gradually changed to fine clumpy crystals from coarse faceted dendrites. When the undercooling reached the maximum value of 310 K, the microstructures contained fine granular crystals. The gain size of primary Si was refined significantly.