Cu-Co系难混溶合金核壳结构演化过程模拟  

Simulation of Core-Shell Structure Evolution of Cu-Co Immiscible Alloys

作　　者：王霖 魏晨 王雷 王军[1] 李金山[1] WANG Lin;WEI Chen;WANG Lei;WANG Jun;LI Jinshan(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China;School of Materials Science and Engineering,Xian University of Technology,Xi'an 710048,China)

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072 [2]西安理工大学材料科学与工程学院,西安710048

出　　处：《金属学报》2024年第9期1239-1249,共11页Acta Metallurgica Sinica

基　　金：国家自然科学基金面上项目No.52174375;陕西省创新能力支撑计划项目No.2020KJXX-073;凝固技术国家重点实验室自主课题项目No.2023-TS-13。

摘　　要：Cu-Co合金具有良好的导电性和巨磁阻性能,在工业上具有很大的应用潜力。由于Cu-Co合金在制备过程中易发生液相分离,导致严重的组分偏析,限制了该合金的应用。因此,探明其凝固组织的演化机制对组织调控工作有着重要意义。本工作主要研究了Cu-Co合金凝固过程中核壳结构的形成机制,并结合实验和数值模拟等方法分析了合金组织的演变过程。模拟基于相场法,并通过耦合流体流动和Marangoni运动,分别进行了3个并行条件的模拟,系统分析了不同条件下该合金不同阶段的微观组织演化过程。模拟结果表明,液相分离引起的流体流动会加速第二相的粗化,同时温度梯度引起的Marangoni运动驱使第二相液滴向中心(高温)聚集,并进一步加速其粗化进程。此外,以3种不同成分Cu-Co合金为例进行模拟,研究了富Co相的体积分数对组织演变产生的影响;并通过与实验制备的凝固组织进行对比,验证了模拟结果的可靠性。Cu-Co alloys demonstrate immense potential for industrial applications due to their excellent properties,including high electrical conductivity and giant magnetoresistance effect.As typical immiscible alloys,Cu-Co alloys are prone to liquid-phase separation during their preparation;as a result,their components undergo severe segregation,limiting their applicability.Thus,investigating and elucidating the evolution mechanism of solidification structures of the Cu-Co alloys is imperative.However,liquidphase separation in these alloys occurs on miniscule time and space scales,and complex physical processes such as diffusion,convection,and heat transfer are also involved.Hence,investigating the kinetic characteristics of alloy solidification and the mechanisms of microstructure formation solely by experimental methods using the existing technology is challenging.Nevertheless,with the continuous advancement of theoretical foundations and computational capabilities of materials,numerical simulations have emerged as an effective tool for investigating the microstructure evolution of immiscible alloys.This study investigates the mechanisms involved in the formation of core-shell structures during the solidification of Cu-Co alloys using a combination of experimental and numerical simulation techniques.Based on the phase-field method,three parallel simulations,incorporating fluid flow and Marangoni motion,were conducted.The microstructure evolution at various stages and under different conditions was systematically analyzed.The simulation results indicated that the fluid flow resulting from liquid-phase separation could expedite the coarsening of the second-phase droplets.Furthermore,Marangoni motion driven by temperature gradients resulted in the coalescence of second-phase droplets at the center(high temperatures),accelerating the coarsening process.The Ostwald ripening phenomenon and coagulation process between the second-phase droplets were simulated,and the growth kinetic mechanisms of the second phase were revealed.I

关 键 词：液相分离 凝固 数值模拟 组织演化 

分 类 号：TG146[一般工业技术—材料科学与工程]