Numerical Simulation of Columnar-to-Equiaxed Transition （CET） in Ti-Al Alloy during Directional Solidification

Wang Kuangfei1; Mi Guofa1; Li Changyun1; Guo Jingjie2; Fu Hengzhi2

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Numerical Simulation of Columnar-to-Equiaxed Transition （CET） in Ti-Al Alloy during Directional Solidification
Issue 9, Pages: 674-678(2007)
Published： 2007 ，
DOI：

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[1]王狂飞,米国发,历长云,郭景杰,傅恒志.Ti-Al合金定向凝固柱状/等轴晶转变的数值模拟[J].特种铸造及有色合金,2007(09):674-678+652.

Wang Kuangfei1, Mi Guofa1, Li Changyun1, et al. Numerical Simulation of Columnar-to-Equiaxed Transition （CET） in Ti-Al Alloy during Directional Solidification. [J]. Special Casting & Nonferrous Alloys (9):674-678(2007)
[1]王狂飞,米国发,历长云,郭景杰,傅恒志.Ti-Al合金定向凝固柱状/等轴晶转变的数值模拟[J].特种铸造及有色合金,2007(09):674-678+652. DOI：

Wang Kuangfei1, Mi Guofa1, Li Changyun1, et al. Numerical Simulation of Columnar-to-Equiaxed Transition （CET） in Ti-Al Alloy during Directional Solidification. [J]. Special Casting & Nonferrous Alloys (9):674-678(2007) DOI：

摘要

采用基于溶质扩散控制模型CA方法

对Ti-Al合金定向凝固过程中柱状晶/等轴晶转变过程进行了数值模拟。模拟结果表明

温度梯度、抽拉速度对柱状晶/等轴晶转变影响定性地符合Hunt解析解。横向晶核间距影响比纵向大;形核过冷度增加

柱状晶/等轴晶转变推迟;柱状晶间距不仅与温度梯度、抽拉速度有关

而且可通过激活预置晶核使其生长为柱状晶而得以调整

特别是温度梯度在30～50K/mm之间

形核有较强的调节柱状晶间距的作用。

Abstract

The CET of Ti-Al alloy during directional solidification was simulated by the cellar automaton （CA） model based on a solute diffusion controlled solidification. The results show that CET is controlled by temperature gradient and drawing velocity

which are accordant with the analytical model of the Hunt

meanwhile

the nuclei spacing in cross section has a stronger effects on CET than the nuclei spacing in longitudinal section. With increasing nucleation undercooling

the CET is postponed. The columnar grain spacing is not only dependent on temperature gradient and drawing velocity

but also influenced by pre-setting nuclei method

especially showing stronger role of adjusting columnar spacing with temperature gradient at 30～50 K/mm.