关键词: 铝硅共晶, 柱晶凝固, 共晶片间距, 形核过冷

Abstract:

Theory of constrained solidification for Al-Si eutectic has been applied to the analysis of columnar solidification process of Al-Si eutectic ingots, and a relational expression of interflake spacing; mean solidification rate and supercooling of nucleation is advanced. The consistency of experimental results with theoretical analysis indicates that the law of constrained solidification for Al-Si eutectic is available to the control of columnar solidification of the ingots.The interflake spacing depends not only on the mean solidification rate, but also on the supercooling of nucleation in the columnar solidification process. Raising of supercooling for nucleation reduces remarkably the interflake spacing, and the melt-refining and melt-superheat are effective ways to raise the level of supercooling.The interflake spacing is proportional to the mean solidification rate with a power factor of（ - 2/3）, and is influenced by the supercooling of nucleation more markedly for small mean solidification rate. However, the microstructure is much even and has little correlation with the dimensions of the ingots.

Key words: aluminium-silicon eutectic, columnar solidification, eu-tectic mterflake spacing, supercooling of nucleation