温度梯度对Ti-45Al合金定向凝固组织演化影响的数值模拟

Numerical Simulation of Effect of Thermal Gradient on Structure Evolution During Directional Solidification of Ti-Al Alloy

采用基于溶质扩散控制模型结合CA方法对Ti-45Al合金定向凝固过程中温度梯度对显微组织演化影响进行了数值模拟。模拟结果表明,随着温度梯度增加,凝固形态经历了树枝晶→胞/枝混合结构→粗胞晶→细胞晶→超细胞晶的转变,而一次胞/枝晶臂间距随着凝固组织变化不断减小。此外,温度梯度很高时,固液界面处溶质富集程度很小,界面处出现溶质截流。

The structure evolution of Ti-Al alloy during directional solidification was simulated to investigate the effects of the applied temperature gradient by applying a solute diffusion controlled solidification model with Cellular Automation（ CA）, and the results have showed that with increasing thermal gradient, the morphology of the interface varies from dendrite to the mixed structure of cell and dendrite to cell to fine cell, finally to superfine cell, which accordingly decrease the dendrite arm spacing. In addition, the high thermal gradient directional solidification also results in reduction in the enrichment of solute at interface, the solute trapping at interface and refinement of cells.