Combining 2D simulations with atom probe tomography to investigate radiation-induced segregation near nanoscale cavities

Abstract Radiation-induced segregation (RIS) is a non-equilibrium phenomenon that can significantly alter local composition and degrade material properties. Although extensive research has focused on RIS near grain boundaries, much less attention has been given to RIS near nanosized cavities, including voids and gas-filled bubbles, which are primary contributors to material swelling. Compared with grain boundaries, cavities exhibit unique characteristics as defect sinks, such as spherical geometry, potentially higher density, and shorter distances between sinks. Although conventional one-dimensional (1D) models can capture basic features of RIS near isolated cavities, our calculations showed that they failed to reproduce experimental RIS profiles near closely spaced bubbles, an arrangement commonly observed in irradiated materials due to heterogenous bubble nucleation. In this study, we combined two-dimensional (2D) simulations with atom probe tomography (APT) experiments to investigate RIS near helium bubbles in a Ni 50 Fe 50 model alloy. The 2D simulations achieved good agreement with the experimental data. Moreover, we identified a non-linear coupling effect between neighboring bubbles: Ni segregation between two bubbles was higher than that from a single bubble, but lower than the linear sum of two isolated bubbles. These results demonstrate that the 2D RIS model is essential for simulating complex RIS behavior near cavities, thereby enabling more accurate predictions of microstructural evolution and property changes in materials under extensive irradiation.