Primary Defect Production in Doped Iron Grain Boundaries during Low Energy Collision Cascades

Abstract: This study explores the intricate interactions between grain boundaries (GBs) and irradiation-induced defects in nanocrystalline iron, highlighting the role of dopants like copper. Utilizing molecular dynamics simulations, the research delineates how GB properties, such as GB energy and defect formation energies, influence the formation and evolution of defects in low energy collision cascades. It reveals that GBs not only augment defect production but also show a marked preference for interstitials over vacancies, a behavior significantly modulated by the cascade's proximity to the GB. The presence of dopants is shown to alter GB properties, affecting both the rate and type of defect production, thereby underscoring the complex interplay between GB characteristics, dopant elements, and defect dynamics. Moreover, the investigation uncovers that the structural characteristics of GBs play a crucial role in cascade evolution and defect generation, with certain GB configurations undergoing reconfiguration in response to cascades. For instance, the reconfiguration of one pure Fe twist GB suggests that GB geometry can significantly influence defect generation mechanisms. These findings point to the potential of GB engineering in developing materials with enhanced radiation tolerance, advocating for a nuanced approach to material design. By tailoring GB properties and selectively introducing dopant elements, materials can be optimized to exhibit superior resistance to radiation-induced damage, offering insights for applications in nuclear reactors and other radiation-prone environments.