Al-Bi过偏晶合金液-液相分离模拟与分析  

Simulation and Analysis of Liquid-Liquid Separation Mechanism of Hypermonotectic Al-Bi Alloy

作　　者：康智强[1] 王恩刚[1] 张林[1] 赫冀成[1] 

机构地区：[1]东北大学材料电磁过程研究教育部重点实验室,辽宁沈阳110004

出　　处：《东北大学学报（自然科学版）》2010年第9期1262-1265,共4页Journal of Northeastern University(Natural Science)

基　　金：国家高技术研究发展计划项目(2007AA03Z519);国家自然科学基金资助项目(50574027;50901019);高等学校博士学科点专项科研基金资助项目(20070145062);高等学校学科创新引智计划项目(B07015)

摘　　要：采用Eulerian法建立过偏晶Al-Bi合金难混溶区凝固过程的数学模型,对过偏晶合金液-液相分解及分离的运动行为进行数值模拟研究,分析两相温度场、运动速度、浓度分布等物性参数对合金凝固显微组织演化的影响.结果表明:先形核的局部区域的过冷度是影响局部大尺寸液滴产生的重要原因;无重力条件下,Marangoni力驱动第二相小液滴向铸件中心区域迁移,导致偏晶合金不能均匀分布;浓度场的不均匀分布是产生宏观偏析的前提,定向运动最终导致两相的宏观分离.A mathematical model was developed by Eulerian method during the solidification process of the hypermonotectic Al-Bi alloy in immiscibility region.A numerical simulation was done for the moving behavior of the liquid-phase decomposition of the alloy and its liquid-liquid separation,thus discussing the effects of twophase temperature field,moving velocity,concentration distribution and other physical parameters on the microstructural evolution during solidification.The results showed that the undercooling in locally prenucleated region is the main influencing factor on the formation of local big-size droplets.Taking no account of gravity,the Marangoni force drives the second-phase droplets to migrate to the casting center,thus resulting in the ununiform distribution of the alloy. The ununiform distribution of concentration is the precondition under which the macrosegregation forms.Eventually,the directional motion results in the twophase macrosegregation.

关 键 词：过偏晶合金 数值模拟 Marangoni力 扩散长大 形核 

分 类 号：TG146[一般工业技术—材料科学与工程]