ABSTRACT
Rate theory (RT) is used to study the size distribution evolution of vacancy clusters (VC), selfinterstitial atom (SIA) clusters (SIAC), and Cr precipitates in neutron-and ion-irradiated Fe-9at%Cr and Fe-12.5at%Cr alloys at T = 573 K with irradiation doses up to 50 displacements per atom (dpa) and a ux of 139 ndpa/s. The size dependence effect of the production rate of point defect clusters is taken into account in the cluster dynamics (CD) modeling of the simultaneous formation of VC and SIAC. Material parameter calibration of the iron matrix has been carried out. In addition, the effect of chromium on the kinetics of the matrix point defects has been taken into account by variation of SIA diffusivity depending on Cr content. The frustration effect, which is typical for the concentrated alloys, has been taken into account empirically by using the thermodynamic free energy expression from CALPHAD with the correction suggested by Bonny et al. The vacancy exchange mechanism has been considered for study of the irradiation-induced or -enhanced formation of α′ precipitates in Fe-Cr alloys. The specic surface tension between the iron matrix and the Cr-rich α′ precipitate and the rate at which Cr monomers are absorbed are used as tting parameters for reproducing the long-term matrix point defects and Cr precipitates evolution in the neutron-and ion-irradiated Fe-Cr alloys observed by transmission electron microscopy (TEM) and small angle neutron scattering (SANS).
