Dislocation behavior in Cu single crystal joints under the ultrasonically excited high-strain-rate deformation  

作　　者：Qiuchen Ma Jingyuan Ma Jianli Zhou Xiaoxiong Zheng Hongjun Ji 

机构地区：[1]The State Key Laboratory of Advanced Welding and Joining,School of Materials Science and Engineering,Harbin Institute of Technology at Shenzhen,Shenzhen 518055,China [2]Sauvage Laboratory for Smart Materials,Shenzhen Key Laboratory of Flexible Printed Electronics Technology,School of Materials Science and Engineering,Harbin Institute of Technology(Shenzhen),Shenzhen 518055,China [3]School of Science,Harbin Institute of Technology at Shenzhen,Shenzhen 518055,China

出　　处：《Journal of Materials Science & Technology》2023年第10期66-77,共12页材料科学技术（英文版）

基　　金：supported by the National Nat-ural Science Foundation of China(No.52175310);A part of the work was also supported by the National Science and Technology Major Project(No.2017-VI-0009-0080);the Guang-dong Province Key Research and Development Program(No.2019B010935001);and the Shenzhen Science and Technology Plan(No.GXWD20201230155427003-20200821172456002).

摘　　要：The coupling effects of ultrasonic excitation and high-strain-rate deformation are the core factors for weld formation during ultrasonic welding.However,interfacial deformation behavior still shrouds in uncer-tainty because of the contradictory features between mutual dislocation retardation caused by severely frictional deformation and ultrasonic-accelerated dislocation motion.[101]and[111]-oriented Cu single crystals which tended to form geometrically necessary boundaries(GNBs)were selected as the welding substrates to trace the uniquely acoustoplastic effects in the interfacial region under the ultrasonically excited high-strain-rate deformation.It was indicated that for a low energy input,micro-welds localized at the specific interface region,and equiaxed dislocation cells substituting for GNBs dominated in the ini-tial single crystal rotation region.As the welding energy increased,continuous shear deformation drove the dynamic recrystallization region covered by equiaxed grains to spread progressively.Limited discrete dislocations inside the recrystallized grains and nascent dislocation cells at the grain boundaries were ob-served in[101]and[111]joints simultaneously,suggesting that the ultrasonic excitation promoted motion of intragranular dislocation and pile-up along the sub-grain boundaries.The interfacial morphology be-fore and after expansion of recrystallization region all exhibited the weakening of orientation constraint on dislocation motion,which was also confirmed by the similar micro-hardness in joint interface.The first-principle calculation and applied strain-rate analysis further revealed that ultrasonic excitation en-hanced dislocation slipping,and enabled dislocation motion to accommodate severe plastic deformation at a high-strain-rate.

关 键 词：Acoustoplasticity Ultrasonic welding Cu single crystal Dynamic recrystallization Dislocation cell High-strain-rate deformation 

分 类 号：O772[理学—晶体学]