中文摘要：

采用液-液混合受控扩散凝固技术（CDS）制备过共晶Al-20%Si 合金，研究高硅合金温度对目标合金组织中初生硅的影响及混合过程中初生硅细化的热力学条件。结果表明：采用液-液混合制备过共晶铝硅合金，可以细化初生硅，初生硅平均尺寸可达到37μm；但随着高硅合金温度的升高，初生硅的平均尺寸增加，板条状和五瓣星状初生硅也增多，当高硅温度超过790℃时，初生硅细化效果丧失。分析得出，只有当混合前两种合金吉布斯自由能的加权平均值小于混合后目标合金在液相线的吉布斯自由能（ final,liquidusmG =-39.3366 kJ）时，初生硅才能得到明显的细化。

英文摘要：

The hypereutectic Al-20%Si alloy was fabricated by liquid-liquid mixing of controlled diffusion solidification （CDS）, and the effect of temperature of high silicon alloy on the microstructure of primary silicon phase and thermodynamic condition of primary silicon refinement in the mixing process were studied. The results show that the primary silicon can be refined obviously and the size of the primary silicon can reach 37 μm in the preparation of hypereutectic Al-20%Si alloy fabricated by liquid-liquid mixing. When the temperature of high silicon alloy increases, the primary phase size increases. When the high silicon temperature is over 790 ℃, the refinement effect of primary silicon is lost. Additionally, when the Gibbs free energy of the liquids prior to mixing is less than the Gibbs free energy of the resultant liquid at its liquidus temperature （ final,liquidusmG =-39.336 6 kJ）, the primary silicon phase will be refined obviously.