Simulation Study On The Interactions Between Edge Dislocation And Radiation-induced Defects In Austenitic Stainless Steel

With the rapid development of modern society,limited traditional energy is rapidly consumed,and nuclear energy has been more researched and applied due to its advantages of cleanliness,environmental protection and low consumption.The long-lasting and high-efficiency output of nuclear energy is inseparable from the safe and stable operation of the reactor.However,the occurrence of several recent nuclear accidents has also made people think a lot about its development,and the research on the safety of the reactor has become a hot spot.Because austenitic stainless steel still has good comprehensive properties under high-temperature irradiation conditions,it is often selected as the core structural material of the reactor.However,after long-term high-energy particle irradiation,many defects such as voids,dislocation loops and stacking fault tetrahedra(SFT)will be generated inside austenitic stainless steel,which will hinder the slip of dislocations and interact with each other.As a result,the performance of the material changes,which affects the safety of the reactor.Therefore,it is of great significance to study the interaction of defects in austenitic stainless steel under irradiation conditions.Since studying irradiated materials experimentally is expensive and tedious,computer simulations are widely used.The microscopic evolution and damage mechanism of the material structure under irradiation conditions can be accurately described by computer simulation,which guides the design of new radiation-resistant materials.Therefore,in this paper,austenitic stainless steel is used as the research system,and the interaction between edge dislocations and three typical irradiation defects(voids,Frank loops and SFT)is simulated by the molecular dynamics method.In this paper,the structure generated by the interaction of defects and the change of critical shear stress(CRSS)during the auction process under different simulation temperatures,defect sizes and initial configurations of action are analyzed,and the effects of different results on the material properties are revealed.At the same time,to obtain more accurate results,the simulated box was randomly alloyed three times before the interaction between edge dislocations and defects.The analysis shows that there are two effects of edge dislocations and voids:(1)the anterior and posterior dislocations of the edge dislocations are separated from the voids,and no constriction is generated;(2)the anterior dislocations of the edge dislocations Dislocations and post-component dislocations are pinned by voids at the same time,resulting in bundles.There are three effects of edge dislocations and dislocation loops:(1)A new stacking fault plane(Sheared)is generated on some edges of the dislocation loop to form a stacking fault complex;(2)The stacking fault inside the dislocation loop disappears and becomes a complete loop,the inertial surface changes(Unfaulting),and(3)a superjog is generated between the loop and the edge dislocation bisector.The interaction between edge dislocations and SFT has two results:(1)the edge dislocations pass directly through the SFT,and(2)the SFT apex atoms gather and the bottom surface disappears.Through the statistics of CRSS values during the interaction between edge dislocations and defects under irradiation conditions,the hindrance of different irradiation defects to the slippage of edge dislocations was explored.The results show that the CRSS values of all types of defects decrease significantly with increasing temperature and become larger with increasing defect size when interacting with edge dislocations(except for the 3 nm dislocation loop at 900 K).For different defects,the CRSS value in the dislocation loop is the largest,and the CRSS value in the stacking fault tetrahedron is the smallest.This is because the Unfaulting mechanism is generated during the interaction between the dislocation loop and the edge dislocation,or the Superjog and the layer are formed.dislocation complexes,so dislocation loops have the greatest resistance to edge dislocation slip.In addition,for both voids and dislocation loops,the CRSS values appear when the anterior or posterior dislocations are pinned from the defect,while the CRSS values for the SFT and edge dislocation processes appear when the SFT is located in the inner layer of the edge dislocation.In this paper,the influence of stacking fault width on defect interaction is discussed.These results will help to understand the irradiation effect of austenitic stainless steel and provide a reference for the structural design of irradiated materials.