Absorption bias: An ideal descriptor for radiation tolerance of nanocrystalline BCC metals

TL;DR

This study introduces the absorption bias as a key descriptor for assessing radiation tolerance in nanocrystalline BCC metals, demonstrating how grain size influences defect recombination and material performance.

Contribution

The paper proposes the absorption bias as a novel, effective descriptor for radiation tolerance, linking it to grain size and defect dynamics in nanocrystalline BCC metals.

Findings

Lower absorption bias enhances defect recombination and radiation resistance.

Nano-crystals improve Fe-based material performance, coarse crystals benefit W-based materials.

Reevaluation of nanocrystalline materials suggests new design strategies for nuclear structural components.

Abstract

To evaluate the radiation tolerance of nanocrystalline (NC) materials, the damage effects of Fe and W as typical body-centered cubic (BCC) metals under uniform irradiation are studied by a sequential multi-scale modelling framework. An ideal descriptor, the absorption bias (the ratio of the absorption abilities of grain boundaries (GBs) to interstitials (I) and vacancies (V)), is proposed to characterize the radiation tolerance of materials with different grain sizes. Low absorption bias promotes defects annihilation through enhancing I-V recombination and optimally tuning its competition with GB absorption. Thus, the lower absorption bias, the higher anti-irradiation performance of NC BCC metals is. Furthermore, by comprehensively considering the mechanical property, thermal stability and radiation resistance, nano-crystals are recommended for Fe-based structural materials but coarse crystals for W-based plasma-facing materials. This work reevaluates the radiation resistance of NC materials, resulting in new strategies for designing structural materials of nuclear devices through manipulating grain sizes.