Effective parameter for the selection of modifying agent for Al-Si alloy

To select effective modifying agent for Al-Si alloys, in addition to conventional parameters such as the crystal structure and lattice constant, the mixing enthalpy, which was calculated by the Miedema model, was newly considered. The large negative value of mixing enthalpy was counted as a new parameter. According to the result of calculation, four elements, including Sr, Y, Sm and Gd, which have large negative mixing enthalpies with Si, were selected as modifying agent for eutectic Si crystals. It was observed that these elements result in the modification of the eutectic Si crystals and that the eutectic depression of the modified alloy is larger than 6 K.