Modelling thermal and irradiation creep with crystal plasticity theory and self-consistent method

Abstract

In order to help comprehend the underlying deformation mechanisms related to irradiation creep of metallic polycrystalline materials, the crystal plasticity theory and viscoplastic self-consistent method are combined in this work. In the developed constitutive laws for single crystals, the influence of irradiation-induced defects on the creep strain rate has been effectively addressed by considering dislocation climb and glide. For the former, dislocation climb with irradiation effect can be enhanced through the absorption of point defects by dislocations, where the steady-state concentration of point defects is affected by the defect sinks including dislocations and defect clusters. As a comparison, dislocation glide may be retarded through the impediment of mobile dislocations by irradiation-induced defects. More importantly, the effect of dislocation static recovery has been incorporated into the dislocation evolution law, which is noticed to play a deterministic role for the annihilation of dislocations during the long-term creep process. In addition, the viscoplastic self-consistent method is taken as a cross-scale way to predict the irradiation creep properties of polycrystals. To validate the developed creep model, experimental data of both single crystalline and polycrystalline nickel has been considered under both thermal and irradiation creep. A good agreement between the theoretical results and experimental data is achieved, which offers a solid basis to further analyze the macroscopic irradiation creep deformation from the aspect of microstructure evolution.