Revisiting dynamics and models of microsegregation during polycrystalline solidification of binary alloy

作     者：Tongzhao Gong Yun Chen Shanshan Li Yanfei Cao Dianzhong Li Xing-Qiu Chen Guillaume Reinhart Henri Nguyen-Thi Tongzhao Gong;Yun Chen;Shanshan Li;Yanfei Cao;Dianzhong Li;Xing-Qiu Chen;Guillaume Reinhart;Henri Nguyen-Thi

作者机构：Shenyang National Laboratory for Materials ScienceInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and EngineeringUniversity of Science and Technology of ChinaHefei230026China Aix Marseille UnivUniversite de ToulonCNRSIM2NPMarseilleFrance 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2021年第74卷第15期

页      面：155-167页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 0817[工学-化学工程与技术] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0802[工学-机械工程] 0702[理学-物理学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：the Science Challenge Project(Grant No.TZ2016004) the Youth Innovation Promotion Association CAS the Youth Talent program of Shenyang National Laboratory for Materials Science(L2019F08) the Special Scientific Projects of Inner Mongolia,and French National Space Center(CNES),Convention N°174800/00。 

主　　题：Microsegregation Grain refinement Cooling rate Back diffusion Phase-field method 

摘      要：Microsegregation formed during solidification is of great importance to material properties.The conventional Lever rule and Scheil equation are widely used to predict solute segregation.However,these models always fail to predict the exact solute concentration at a high solid fraction because of theoretical assumptions.Here,the dynamics of microsegregation during polycrystalline solidification of refined Al-Cu alloy is studied via two-and three-dimensional quantitative phase-field simulations.Simulations with different grain refinement level,cooling rate,and solid diffusion coefficient demonstrate that solute segregation at the end of solidification(i.***.when the solid fraction is close to unit)is not strongly correlated to the grain morphology and back diffusion.These independences are in accordance with the Scheil equation which only relates to the solid fraction,but the model predicts a much higher liquid concentration than simulations.Accordingly,based on the quantitative phase-field simulations,a new analytical microsegregation model is derived.Unlike the Scheil equation or the Lever rule that respectively overestimates or underestimates the liquid concentration,the present model predicts the liquid concentration in a pretty good agreement with phase-field simulations,particularly at the late solidification stage.