CA-LBM模型模拟Al-4.7%Cu固溶体合金成分分布和枝晶形貌  

Simulation of composition and dendritic morphology of Al-4.7%Cu solid solution alloy with cellulnent distributiar automaton and lattice Boltzmann method

作　　者：杨莹莹[1] 李日[1] 周靖超[1] 赵朝阳[1] 

机构地区：[1]河北工业大学材料科学与工程学院,天津300130

出　　处：《材料热处理学报》2016年第10期186-191,共6页Transactions of Materials and Heat Treatment

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：建立了耦合温度场、流场、溶质场的CA-LBM(元胞自动机-格子玻尔兹曼方法)数值模型,并用该模型研究了Al-4.7%Cu固溶体合金的凝固过程。模拟结果验证了模型的合理性,再现了合金凝固过程中的枝晶形貌和溶质偏析,并定量研究了自然对流、初始温度对溶质分布和微观组织的影响。研究表明,自然对流对枝晶形貌有明显的影响,使枝晶生长非对称化,即迎流方向的枝晶生长得到促进,顺流方向的枝晶生长受到抑制。初始温度对凝固进程和枝晶形貌影响较大,降低初始温度,枝晶生长加快且产生了二次枝晶,并造成枝晶尖端固液界面处溶质浓度偏高,加重了溶质偏析。A numerical model combining the cellulnent automation（ CA） and the lattice Boltzman method（ LBM） is developed to simulate heat transport,fluid flow,solute diffusion and dendritic growth,and then by this model the solidification process of Al-4.7% Cu alloy is investigated.The simulation results reproduce the dendrite morphology and solute segregation in the solidification process,and prove the rationality of the model.The effects of natural convection and cooling rate on the solute distribution and dendritic morphology are quantitively studied by the model.The results show that the natural convection has a significant effect on the morphology of the dendrites,which makes the growth of dendritic crystals not symmetrical,that is to say,the dendritic growth in the upstream direction of the natural flow is promoted,as well as the dendritic growth in the downstream direction is inhibited.In addition,the undercooling also has great effect on the rate of dendritic growth and dendrite morphology.As the degree of undercooling is increased,the dendrite growth is accelerated and secondary dendrite appears; and in the end,the solute concentration is increased at the solid / liquid interface of the dendrite tip,which increases the solute segregation across the whole region.

关 键 词：合金凝固 CA-LBM模型 自然对流 枝晶生长 溶质富集 

分 类 号：TG146.1[一般工业技术—材料科学与工程]