Atomistic study on the microscopic mechanism of grain boundary embrittlement induced by small dense helium bubbles in iron  

作　　者：Lei Peng Yong-Jie Sun Jing-Yi Shi Yi-Fei Liu Shang-Ming Chen Liu-Liu Li 

机构地区：[1]State Key Laboratory of Particle Detection and Electronics,University of Science and Technology of China,Hefei 230026,China [2]School of Nuclear Science and Technology,University of Science and Technology of China,Hefei 230027,China [3]Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China

出　　处：《Nuclear Science and Techniques》2024年第3期84-95,共12页核技术（英文）

基　　金：supported by the National Natural Science Foundation of China(Nos.12175231 and 11805131);Anhui Natural Science Foundation of China(No.2108085J05);the National Key Research and Development Plan of China(No.2018YFE0307101);the Collaborative Innovation Program of the Hefei Science Center,CAS(Nos.2021HSC-CIP020 and 2022HSC-CIP009)。

摘　　要：The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion reactors.In order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics methods.The results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile GBs.The atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation mechanism.However,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at fractures.For bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation angle.Interestingly,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.

关 键 词：Helium bubble Grain boundary EMBRITTLEMENT Reduced activation ferritic martensitic steel Molecular dynamics Bain path 

分 类 号：TL341[核科学技术—核技术及应用] TL62