Atomistic Simulation Of The Interaction Of Edge Dislocation In BCC Iron And Copper Precipitates

Radiation-induced defects can be formed under working conditions of metals in the core structure of nuclear power plant. It will result the significant change of the material mechanical properties. From the early research, copper precipitates in pressure vessel ferritic alloys are particularly important. So, understanding the change mechanisms is of great meaningful for estimation of lifetime of power plant component. In this thesis, the energy minimum method and molecular dynamics method are used to study the edge dislocation motion in bcc iron and the interaction of dislocation and copper precipitates.In the article, conjugate gradient method (CG) and molecular dynamics (MD) method are introduced firstly. After that, some simple dislocation theory is also discribed, such as Burgers vector, dislocation motion, and precipitates strengthening. The following are the actual simulation and results discussion, including the model, the process and the results.From the simulation results, some phenomena and conclusions are obtained.(1) Stress must overcome the Peierls stress, dislocation motion can be come on. In the temperature region near 10K, dislocation motion is sensitively to the temperature variation. But, from 100 to 300K, temperature has slight effect to dislocation motion. The speed of dislocation is increase with the applied shear stress. The details of the parameter is shown in the article.(2) Copper precipitates will baffle the movement of dislocation. In another words, Copper precipitates attract the dislocation. Precipitate diameter, precipitates distance and the concentration of precipitates are the so important parameters about the precipitates strengthening. The Critical Resolved Shear Stress (CRSS) is the parameter which is a token of the intensity of the strengthening. The CRSS will be increase with the diameter of the precipitates increase. It will be decrease with the increase of precipitates distance. In this simulation, it is easy to find that precipitates distance has no effect to the change of the critical angle formed by the two bowing arms of the pinned dislocation. At last, some new results are compared with former researcher's results and earlier continuum treatments.