Phase-field simulation of forced flow effect on random preferred growth direction of multiple grains  

层流作用下随机取向多晶粒生长的相场法模拟(英文)

作　　者：王军伟[1] 朱昌盛[1,2] 王智平[1,3] 冯力[1] 肖荣振[1] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,兰州730050 [2]兰州理工大学CAD中心,兰州730050 [3]甘肃省有色金属及复合材料工程研究中心,兰州730050

出　　处：《Transactions of Nonferrous Metals Society of China》2011年第7期1620-1626,共7页中国有色金属学报（英文版）

基　　金：Project(10964004) supported by the National Natural Science Foundation of China;Project(20070731001) supported by Research Fund for the Doctoral Program of China; Project(096RJZA104) supported by the Natural Science Foundation of Gansu Province,China;Project(SB14200801) supported by the Doctoral Fund of Lanzhou University of Technology,China

摘　　要：The random distribution problem of dendrite preferred growth direction was settled by random grid method.This method was used to study the influence of forced laminar flow effect on multiple grains during solidification.Taking high pure succinonitrile （SCN） undercooled melt as an example,the forced laminar flow effect on multiple grains was studied by phase-field model of single grain which coupled with flow equations at non-isothermal condition.The simulation results show that the random grid method can reasonably settle the problem of random distribution and is more effective.When the solid fraction is relatively low,melt particles flow around the downstream side of dendrite,and the flow velocity between two dendrite arms becomes high.At the stage of solidification time less than 1800Δt,every dendrite grows freely;the upstream dendrites are stronger than the downstream ones.The higher the melt flow rate,the higher the solid fraction.However,when the solid fraction is relatively high,the dendrite arm intertwins and only a little residual melt which is not encapsulated can flow;the solid fraction will gradually tend to equal to solid fraction of melt without flow.为了更客观地再现强迫层流对多晶粒凝固过程的影响,自行设计了随机格子法以解决多个枝晶择优生长方向随机分布问题。以高纯丁二腈(SCN)为例,采用耦合流场的单相场模型研究强迫层流对多晶粒非等温生长过程的影响。结果表明:随机格子法可以更合理地处理枝晶择优取向随机分布问题,计算效率较高。当固相率较低时,熔体质点绕过枝晶流向下游侧,两枝晶臂之间的熔体流动速度值变大;在凝固计算时间小于1800Δt时,各个枝晶自由生长,上游侧枝晶臂均比下游侧枝晶臂发达;并且,熔体流入速度越快,固相率越高。当固相率较高时,多个枝晶臂相互交织,仅有未被枝晶包裹的残留熔体可以流动;同时,固相率趋于与熔体无流动时的固相率相同。

关 键 词：phase-field method multiple grains laminar flow preferred growth direction computer simulation SOLIDIFICATION flow velocity 

分 类 号：O781[理学—晶体学]