Strong size effect on deformation twin-me diate d plasticity in body-centered-cubic iron  

作　　者：Ligong Zhao Guoxujia Chen He Zheng Shuangfeng Jia Kaixuan Li Renhui Jiang Lei Li Ying Zhang Huayu Peng Peili Zhao Ziyang Huang Jianbo Wang 

机构地区：[1]School of Physics and Technology,Center for Electron Microscopy,MOE Key Laboratory of Artificial Micro-and Nano-structures,and Institute for Advanced Studies,Wuhan University,Wuhan 430072,China [2]Suzhou Institute of Wuhan University,Suzhou,Jiangsu 215123,China [3]Wuhan University Shenzhen Research Institute,Shenzhen,Guangdong 518057,China

出　　处：《Journal of Materials Science & Technology》2023年第13期235-242,共8页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.52071237,12074290,51871169,52101021,and 12104345);the Natural Science Foundation of Jiangsu Province (No.BK20191187);the Young Top-notch Talent Cultivation Program of Hubei Province,the Science and Technology Program of Shenzhen (No.JCYJ20190808150407522);the China Postdoctoral Science Foundation (No.2019M652685).

摘　　要：Deformation twinning serves as an important mode of plastic dissipation processes in nanoscale body-centered cubic(BCC)metals,but its origin and spatio-temporal features are mysterious.Here,applying in situ tensile experiments,we report a strong size effect on mediating the twinning behaviors and twin boundary(TB)-dislocation interaction mechanisms in BCC iron(Fe)nanowires(NWs).There exists a critical diameter(d)of∼2.5 nm,above which the deformation twinning rather than dislocation slip dominates the plasticity.Unlike the traditional reflection TBs,the intermediate isosceles TBs are consis-tently observed as mediated by the 1/12<111>partial dislocations.Moreover,we uncover two distinct TB-related deformation mechanisms,including twin variant re-orientation and TB cracking for NWs with d<17 nm and d>17 nm,respectively.Further molecular dynamics and statics simulations provide the basic underlying mechanisms for size-dependent plasticity,which have been largely overlooked in previous experimental investigations.Our findings highlight the importance of grain size in mediating the deformation behaviors in Fe,serving as possible guidance for exploring single-crystalline and poly-crystalline Fe-based materials(e.g.steel)with optimized mechanical performance.

关 键 词：Size effect Full dislocation Isosceles twin boundary Twin variant rotation TB cracking 

分 类 号：TG132.3[一般工业技术—材料科学与工程]