超声凝固条件下二元Al-12.6%Si共晶合金的组织演变机制研究  

Ultrasonic solidification and microstructural evolution of binary Al12.6%Si eutectic alloy

作　　者：王宝剑 王建元[1] 吴文华 翟薇[1] 王旭[1] 靳占奎 魏炳波[1] WANG BaoJian;WANG JianYuan;WU WenHua;ZHAI Wei;WANG Xu;JIN ZhanKui;WEI BingBo(School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710129,China)

机构地区：[1]西北工业大学物理科学与技术学院,西安710129

出　　处：《中国科学：技术科学》2023年第3期353-362,共10页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:52088101,51922089,51727803);陕西省重点研发计划(编号:2020ZDLGY13-03)资助项目

摘　　要：在三维高强超声场中实现了二元Al-12.6%Si共晶合金的动态凝固过程,探索了其组织演变机制.结果表明,静态凝固条件下形成典型的共晶组织,其中(Si)相呈不规则薄片状,而α(Al)相为枝晶状.三维超声作用下,空化引起熔体过冷和声流改变温度场和溶质场的分布特征,使两共晶相独立形核,从而形成离异共晶组织.超声的高频振动效应增加了(Si)相的孪晶生长几率,导致大量交错孪晶(Si)相产生.由于超声降低了两相之间的界面能,共晶组织平行生长取向程度升高,同时其显微硬度显著提高.Three-dimensional(3D)ultrasounds were introduced into liquid Al-12.6%Si eutectic alloy to explore its dynamic solidification and structural evolution mechanisms.Under static solidification,a typical eutectic microstructure was composed of irregular flake(Si)and dendritic matrixα(Al)phases.Once 3D ultrasounds were applied,the undercooling increase caused by ultrasonic cavitation promoted the independent nucleation of eutectic(Si)andα(Al)phases.Meanwhile,the uniform temperature field and solute field secured by acoustic streaming made these two eutectic phases grow isotropically.As a result,a divorced eutectic structure formed,consisting of the blocky(Si)and globularα(Al)phase.The high-frequency vibration effect of ultrasound increased the twinning probability of the Si phase,leading to lots of multiple twin(Si)phases with intercrossing interfaces.The intensive ultrasound reduced interfacial energy between(Si)andα(Al)phases and enhanced the quantity of parallel growth-oriented crystalline planes,which improved the microhardness of ultrasonicated binary Al-12.6%Si eutectic alloy.

关 键 词：超声凝固 共晶生长 组织演变 空化效应 声流效应 

分 类 号：TG146.21[一般工业技术—材料科学与工程]