Statistical study of displacement cascades in Ni and FeNiCr alloys: Understanding the influence of potential and composition on primary damage modeling

This work investigates the interaction between high-energy particles and metals, focusing on the primary irradiation damage through extensive molecular dynamics simulations. The cascades are simulated using empirical interatomic potentials and cover an extensive range of energies (above and below the sub cascade threshold), ranging from 0.5 keV to 120 keV. These potentials are characterized using properties associated with point defects, surface energy, stacking fault energy, threshold displacement energy, and Quasi-Static Drag (QSD). The data obtained from the simulations are analyzed using specific descriptors, which helps improve our understanding of the primary damage.

A database containing approximately 15,000 displacements cascades in both nickel (Ni) and the FeNiCr alloy has been generated by molecular dynamics. To assess these extensive datasets, a variety of statistical methodologies, including MANOVA, ANOVA, k means and correlation matrices, were employed. Utilizing these analytical tools and statistical descriptors, the study investigated the influences of potentials and compositions on defect production in both nickel (with 3 different Ni potentials) and 5 different FeNiCr compositions. A comparative analysis between the outcomes of potential and alloy analyses was conducted to determine the predominant effect.

Potentials exhibit varied effects, particularly post-fragmentation energy, influencing cascade fragmentation and mono defects. Alloy compositions showcase differing defect production patterns, with Ni generating more defects, while alloys produce an elevated number of mono-interstitials and interstitial clusters. Notably, the study highlights the impact of the Ni fragmentation energy, identifying differing effects below and above this threshold, with a pronounced influence on interstitials.