| Abstract Scope |
Understanding the effects of nanoscale defects on the long-term integrity of next generational nuclear structural materials is challenging due to limitations in experimental resolution and timescale. Computational approaches, such as molecular dynamics (MD) and kinetic Monte Carlo (KMC), have proven valuable in elucidating defect-driven degradation mechanisms. While MD is effective at modeling primary defect production, its applicability is limited to short timescales. KMC, on the other hand, extends to longer times but relies on pre-defined defect properties and lacks atomic resolution. In this presentation, I will highlight recent insights into extended defect accumulation in ion-irradiated ferritic iron using the Defect Rate-Based Long-Time Dynamics (DRLD) method—an approach specifically developed to efficiently model systems with high defect concentrations. Ion cascade simulations are initiated using 30 keV primary knock-on atoms (PKAs), and the resulting defect evolution is tracked over extended timescales. Beyond irradiation studies, the DRLD method is also applied to investigate defect clustering and anisotropic diffusion in bcc-Fe and fcc-Ni under uniaxial stress. Defects are introduced either by injecting Frenkel pairs or by creating isolated vacancies, followed by evolution under either stress-free or 6 GPa uniaxial loading in various crystallographic orientations. These simulations reveal distinct patterns of defect clustering and directional dependence in diffusion behavior, particularly for interstitial and vacancy clusters of varying size. Together, these findings contribute to a more comprehensive understanding of irradiation-induced degradation mechanisms in nuclear materials, capturing the influence of stress, crystal structure, and defect interactions with greater fidelity than conventional techniques. |