基于CA方法的Ti-45Al合金定向凝固过程微观组织模拟

Numerical Simulation of Directional Solidification Microstructure of Ti-45Al Alloy Based on CA Method

采用CA方法建立了Ti-45Al(at.%)合金定向凝固过程中的组织演变数值计算模型,考虑了二元合金包晶反应过程,对液态金属冷却定向凝固过程中Ti-45Al合金的组织演变进行了模拟。模拟结果表明,定向凝固组织分为初生等轴晶组织、稳定生长的柱状晶以及中间过渡区域3部分,柱状晶一次臂间距随抽拉速度增大而减小。Ti-45Al合金在0.1 mm/min抽拉速度条件下,得到了以初生β相为主的凝固组织,在枝晶间溶质富集处有少量的包晶相析出,与相关试验结果基本一致。

The numerical model of microstructure evolution during directional solidification process of Ti-45Al（at.%） alloy was established based on CA method,which takes into account the binary alloy peritectic reaction process and simulated the directional solidification process with indium-gallium alloy liquid metal cooling.Simulation results show that the solidified microstructure can be divided into three regions consisting of primary equiaxed grain,stable columnar grain growth region and the transition region.The primary dendrites arm spacing of the columnar grains decreases with the increasing of the withdrawing rate.At the withdrawing rate of 0.1 mm/min,the simulation region was dominated by primary β phase,and in the solute-rich interspace between β dendrites a small number of peritectic α phase can be found,which matched the published experimental results very well.