Interaction Of 1/3[11(?)0] Edge Dislocation With Defect Obstacles In ?-zirconium

Zr alloys are important structural materials of many commercial nuclear power plants and their service properties affect both lifetime and safety during operation,transportation and storage of fuel assemblies.The cascade collision of high-energy particles under irradiation ambient scattering in the inner of metal cause microstructure in different kinds of shape and size,i.e.defect clusters,micro-void and dislocation.Within these micro-structure under plastic deformation,dislocation glide is pinned by these obstacles and lead to a accumulation of dislocation and finally cause plastic hardening and reduce ductility of metals.The studies of point defects of Zr and its evolution under irradiation ambient become significant for understanding the evolution of Zr alloy under irradiation.In this paper we used EAM potential to investigate interaction of 1/3[11(?)0]edge dislocation with obstacles such as void,precipitate and SIAs-clusters in a-zirconium by molecular dynamics.Firstly,the physical properties of Zr and point defects were calculated.The calculated values of Zr agree well with experiment values and those of other computational works.This indicates that this EAM potential is suitable for studies of Zr.Secondly,the stable configurations and y-surface of 1/3<11(?)0>(0001)and 1/3<11(?)0>(1100)edge dislocation were investigated.The results indicate that 1/3<11(?)0>(0001)edge dislocation dissociate into two part,namely the two partial dislocation with Burgers vector of<1010>,while,1/3<11(?)0>(1100)remains its original Burgers vector as a perfect dislocation.The Pierce Stress of two kinds of dislocation was calculated and the results indicate that the CRSS needed for prism slip is much larger(as much as 5 times)than basal slip under the same temperatures.Finally,the interactions of dislocation and obstacles(including void,precipitates and SIAs-clusters)were studied and their unpinnig mechanisms were also obtained.The results show the pining influence of obstacles play more roles on the 1/3<11(?)0>(0001)edge dislocation with increasing of 100%to 300%of its CRSS than 11/3<11(?)0>(1100)edge dislocation with increasing only 20%of its CRSS.As for mechanisms of break away of a void,the two kinds of dislocations evolve similarly,dislocation absorbs a few vacancies and climbing.For breaking away of a precipitates,the two kinds of dislocations act different.The 1/3<11(?)0>(0001)edge dislocation breaks away through dissociation of dislocation loop,while 1/3<11(?)0>(1100)edge dislocation exist three probably unpinning mechanisms.Moreover,there's a different of breaking way mechanism of SIAS-clusters in the same size for two dislocations.For 1/3<11(?)0>(0001),it absorbs all SIAs atoms and acquires a circle loop,while 1/3<11(?)0>(1100)leaves SIAs-clusters in their original shape after it breaks away.