Rate theory investigation of influence of cascade cluster formation and solute trapping on point defect agglomeration and extended defect evolution

Abstract

Using a composite model of point defect behavior and microstructural evolution, the influence of cascade vacancy cluster formation and vacancy trapping at solute atoms on the point defect fluxes, point defect clustering and extended defect development was investigated. The point defect model calculates the concentrations of isolated and trapped point defects, and of simple or complex clusters. The extended defect model consists of individual rate theory models describing the evolution of cavities, Frank loops and network dislocations. Cascade vacancy clusters were observed to become the dominant sink for point defects in the early stages of irradiation at low to intermediate temperature. Therefore, the sink strength of the vacancy clusters largely determines the point defect flux and agglomeration rates. The calculations also showed that solute traps affect the irradiated microstructure to a large extent for certain combinations of trap concentration and trapping energy. Both the trap concentration and trapping energy have a non-monotonic effect on vacancy clustering though they do not change the interstitial flux significantly.