Al-Cu-Zn合金微观偏析的实验和Scheil模型研究

STUDY OF MICROSEGREGATION IN Al-Cu-Zn TERNARY ALLOYS BY EXPERIMENT AND SCHEIL MODEL

应用相图计算耦合Scheil模型、简单Scheil方程和实验比较研究了Al-Cu-Zn合金单相凝固过程的凝固路径和微观偏析,相图计算耦合Scheil模型的计算结果显示,Al-Cu-Zn合金单相凝固结束点的溶质含量与凝固初始点的成分同步变化,溶质含量和溶质分凝系数随凝固过程的进行不断增加;在热力学计算出合金分凝系数的基础上,简单Scheil方程可以计算初生相含量,从不同溶质得到的计算结果是自洽的,并与相图计算耦合Scheil模型的预测值一致;实验测定了不同成分铝合金的共晶含量和枝晶间距,实验数据与模型结果基本一致.

The solidification path and microsegregation during primary solidification of Al-Cu-Zn alloy were investigated comparably by CALPHAD coupled with Scheil model, simple Scheil equation and experiment. It was indicated by the CALPHAD that the solute content at the end point of primary solidification changes synchronistically with the start point, solute content in dendritic arm and the partition coefficient increase with the solid fraction. Simple Scheil equation was shown to be able to calculate the eutectic amount on the base of partition coefficient calculated by thermodynamics, its prediction for the different solutes is self-consistent and agreeable with the CALPHAD. The eutectic amount and SDAS was measured in DC experiment and compared to model value, it was shown that the experimental data are in agreement with the model prediction.