铝硅共晶柱状晶凝固

 将强制凝固的理论和试验结果应用到铝硅共晶铸锭柱晶凝固过程,得到了共晶片间距同凝固速度、形核过冷间的关系。柱晶凝固时共晶片间距同平均凝固速度因子V~(-2/3)成正比,还同凝固时形核过冷密切相关,形核过冷增加使共晶片间距减小。文中讨论了影响形核过冷的诸因素和凝固组织均匀性问题。

AN INVESTIGATION ON COIUMNAR SOLIDIFICATION OF Al-Si EUTECTIC

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.