Grain Boundary Defect Production during Successive Displacement Cascades on a Tungsten Surface

Abstract

This study delves into the complex mechanisms of defect production and accumulation in nanocrystalline tungsten under irradiation, with a particular focus on the interplay between grain boundaries and free surfaces. Through molecular dynamics simulations, the research explores how grain boundaries act as sinks for irradiation-induced defects, a critical aspect in designing nanomaterials with enhanced radiation tolerance. The investigation leverages a novel Modified Wigner-Seitz Analysis to accurately quantify defect trends amidst dynamic surface reconstruction, providing a nuanced understanding of defect distribution in response to irradiation. This methodology underscores the intricate relationship between defect dynamics and the nano-scale structure of materials, specifically highlighting the role of interfaces in mediating these dynamics. The findings reveal a complex balance between defect production, surface interactions, and the influence of pre-existing defects and temperature on the primary defect production process. Surfaces are shown to amplify defect production due to biased accumulation of interstitials, alongside suppressed defect recombination, emphasizing the nuanced nature of defect dynamics in irradiated materials. This research contributes significantly to the fundamental understanding of defect formation and evolution in irradiated tungsten, offering insights that are instrumental in the development of nanomaterials poised for applications in extreme irradiation environments, such as fusion reactors, thereby advancing the field of materials science and engineering.