Stress-Induced Neutron Irradiation Voids of Austenite Steel Using Phase Field Method
Irradiation swelling caused by irradiation voids is responsible for the failure of long-term serving austenite steel in the reactor core.A mesoscale phase field model coupled with rate theory and micro-elastic theory was used to investigate the stress effects on void microstructure of Fe-Cr austenite steel,when the applied global stress and local dislocation stress field were considered.Results show that the applied stress shortens the incubation period of nucleation of voids and accelerates the growth of voids,and the voids evolve into fusiform eventually.Voids in the stressed state have a larger radius and lower density compared with that in the stress-free state.The larger the applied stress,the larger the average radius and volume fraction,the smaller the number,and the more significant the morphology reconstruction.The local elastic stress field of dislocation dipole and dislocation array attracts vacancies to preferentially nucleate and grow around the dislocation nucleus.Compared with the dislocation-free system,the voids are denser and finer when dislocations exist,but the volume fraction of voids persists.In contrast,the applied stress should probably cause server swelling than dislocations in Fe-Cr alloys.The results of this study is conducive to the evaluation of microstructure aging and property decline of in-core austenitic steel.