对流作用下Al-4.7%Cu合金枝晶生长的形貌特征和成分分布的数值模拟  

Simulation of Dendritic Morphology and Constituent Distribution of Al-4.7%Cu Alloy Under Convection

作　　者：周靖超[1] 李日[1] 杨莹莹[1] 赵朝阳[1] 

机构地区：[1]河北工业大学材料学院,天津300130

出　　处：《航空材料学报》2016年第4期1-9,共9页Journal of Aeronautical Materials

基　　金：国家自然科学基金(51475138);国家重点基础研究发展计划(2011CB610402)

摘　　要：建立了用于模拟Al-4.7%Cu(质量分数)单相固溶体合金凝固过程温度场、流场、溶质场以及微观组织模拟的元胞自动机-格子玻尔兹曼方法(CA-LBM)数值模型,分析对流作用下枝晶生长的形貌与成分变化。模型处理溶质场计算中固液(S/L)界面处溶质的分配过程,使浓度场的变化和实际的传输过程更加相符。计算结果表明,与不计入流动过程的纯扩散型合金凝固过程相比较,对流对合金枝晶形貌的影响显著,呈现非对称生长形貌。在强制对流条件下,枝晶晶粒大小呈均匀化趋势,枝晶间的局部区域的成分更加均匀,在整体凝固区域内的成分呈现出上游到下游的一定的梯度化趋势。A new two-dimensional modeling approach combining the cellular automaton（ CA） and the lattice Boltzmann model（ LBM）was developed to simulate heat transport,fluid flow,solute diffusion,and dendritic growth in the process of the Al-4. 7% Cu solidification of the single-phase solid solution alloy. And the changes of dendritic morphology and constituent under convection were analyzed.The present model improved the solutal distribution approach at the solid-liquid（ S / L） interface,which made the change of solute more consistent with the actual transport. The simulation results demonstrate that dendritic morphology is strongly influenced by forced convection,comparing with that without accounting for convection. Under the forced convection,the dendrite grain sizes tend to be similar; the constituent in the interdendritic region is more homogeneous; and the composition in the whole solidification region exhibits a certain gradient trend from upstream to downstream.

关 键 词：合金凝固 微观组织模拟 CA-LBM 成分分布 枝晶形貌 

分 类 号：TG146.2[一般工业技术—材料科学与工程]