中文摘要：

液体 Al-12wt.%Sn-4wt.%Si 的粘性的温度依赖与一台高温度的粘性仪器被学习。melt 的粘性的异常变化在冷却过程在 1,103 K 和 968K 被发现，它显示 melt 的异常结构的变化。异常结构的变化在 melt.According 与原子簇的尺寸和激活精力的突然的减少被联系到异常结构的变化的温度，这被计算，融化热处理过程(熄灭从过热到倒温度)在 Al-12wt.%Sn-4wt.%Si 上被执行融化在流以前，试图阻止小原子簇更高的温度降低流的温度。结果建议在在 melt 的流的温度的相对小的原子簇能产生一在随后的团结过程的成核深下面凉下来、精制当演员组结构。在从过热到倒温度被熄灭以后，相对小的原子簇，在 melt 的特别 Si-Si 簇将与保持时间成长到平衡状态(相对大的原子簇) ，导致在当演员组结构的 Si 形态学的突出的变粗。

英文摘要：

The temperature dependence of the viscosity of liquid Al-12wt.%Sn-4wt.%Si was studied with a hightemperature viscosity apparatus.Anomalous changes of viscosity of the melt were found at 1,103 K and 968 K in the cooling process,which indicates anomalous structural changes of the melt.It is calculated that the anomalous structural change is associated with an abrupt decrease of atomic clusters＇size and activation energy in the melt.According to the temperature of the anomalous structural changes,melt heat treatment process（quenching from superheat to pouring temperature） was performed on Al-12wt.%Sn-4wt.%Si melt prior to pouring,aimed to keep the small atomic clusters from higher temperature to lower pouring temperature.The results suggest that relatively small atomic clusters at the pouring temperature in the melt could generate a deep under-cooling of nucleation in the subsequent solidification process,and refine the as-cast structure.After being quenched from superheating to pouring temperature,the relatively small atomic clusters,especially the Si-Si clusters in the melt will grow to equilibrium state（relatively big atomic clusters） with holding time,resulting in the prominent coarsening of the Si morphology in the as-cast structure.