Impact of chemical short-range order on radiation damage in Fe-Ni-Cr alloys

TL;DR

This study uses molecular dynamics simulations to show how chemical short-range order in Fe-Ni-Cr alloys influences defect behavior and radiation damage, revealing that CSRO affects defect diffusion, clustering, and microstructural evolution.

Contribution

It demonstrates the impact of CSRO on radiation-induced defect dynamics and microstructural evolution in Fe-Ni-Cr alloys, highlighting the importance of considering CSRO in radiation damage studies.

Findings

High CSRO reduces defect diffusivity due to trapping effects.

Interstitial clusters are Cr-rich and localize near Cr-rich CSRO domains.

CSRO evolves dynamically under irradiation, reaching a steady state.

Abstract

Chemical short-range order (CSRO), a form of nanoscale special atom arrangement, has been found to significantly alter material properties such as dislocation motion and defect dynamics in various alloys. Here, we use Fe-Ni-Cr alloys to demonstrate how CSRO affects defect properties and radiation behavior, based on extensive molecular dynamics simulations. Statistically significant results are obtained regarding radiation-induced defect propensity, defect clustering, and chemical mixing as a function of dose for three CSRO levels. The perfect random solution as an energetically unfavorable state (negative stacking fault energy) shows the strongest tendency to enable diffusion, while a high CSRO degree scenario generally reduces the effective defect diffusivity due to trapping effects, leading to distinct defect dynamics. Notably, in the high-CSRO scenario, interstitial clusters are Cr-rich and interstitial loops preferentially reside in/near the Cr-rich CSRO domains. It is also identified that CSRO is dynamically evolving in a decreasing or increasing manner upon continuous irradiation, reaching a steady-state value. These new understandings suggest the importance of incorporating the effect of CSRO in investigating radiation-driven microstructural evolution.