枝晶尖端生长速度对凝固组织数值模拟的影响研究——Ivantsov函数近似方式的确定

Research on the Effect of Dendrite Tip Growth Velocity on the Microstructure Simulation Determination of the Approximation of Ivantsov Function

利用ProCAST的CAFE模块模拟铝合金的凝固组织,比较不同生长动力学系数下的模拟结果来说明枝晶生长速度对数值模拟结果的影响。对比发现,相同凝固条件下,枝晶生长速度越小,凝固组织中柱状晶区比例越小,等轴晶区比例越大。计算过程表明,采用不同的方法处理描述枝晶尖端稳态扩散的Ivantsov函数,得到的枝晶生长速度不同。通过分析Al-7%Si及Al-4.15%Mg在不同的Ivantsov函数近似下的枝晶生长动力学,本文认为,应用KGT模型时,采用Ivantsov函数的二级近似比较合适。

The microstructure of the aluminum alloy was simulated by CAFE module of ProCAST.By comparing the simulated microstructures,the effect of dendrite velocity on the numerical simulation results was illustrated.Under the same solidification conditions,faster is the velocity,bigger is the columnar region and also smaller is the equiaxed region.Different approximations of Ivantsov function will get different velocities of the dendrite tip,instead of similar results,while solving KGT model.Through analysis of dendrite growth kinetics of Al-7%Si and Al-4.15%Mg under different approximations of Ivantsov function,the following conclusion can be got： second approximation of Ivantsov function is reasonable for solving KGT model.