二元合金非等温凝固枝晶生长的相场法模拟

Numerical Simulation of Non-isothermal Dendritic Growth of Binary Alloy Using Phase-field Method

利用相场模型与溶质场、温度场进行耦合计算,以Al 4 5%Cu合金为例模拟了二元合金非等温凝固和等温凝固的等轴枝晶生长过程。研究了扰动对过冷合金熔液中的等轴枝晶生长以及溶质场和温度场的分布的影响。结果表明:扰动的引入可以促进枝晶的二次晶臂生长,并使固相中的最高温度提高,但基本不影响枝晶尖端稳定行为;在枝晶生长过程中枝晶尖端的浓度和温度的梯度最大;在非等温凝固时枝晶没有等温凝固时发达,并且凝固界面的溶质浓度也会降低。

The dendritic growth process during nonisothermal and isothermal solidifications in a Al45%Cu binary alloy was simulated using the phasefield model.Solute diffusion equation and heat transfer equation were solved simultaneously.The effect of noise on the dendritic growth, solute and temperature profile in undercooled liquid alloy were investigated.The results indicate that the noise could trigger the growth of the secondary arms, and increase the highest temperature in solid;but not influence the tip operating state. The solute and temperature gradients in the tip are the highest. Increased melt tempeture reduces sources of instability, which leads to less developed structure of the nonisothermal dendritic, and reduces the value of the composition at the interface.