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

Chemical short-range order (CSRO), as a nanoscale atomic feature, has been found to significantly alter material properties 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 as a function of dose for three CSRO levels. The 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. Also, CSRO is dynamically evolving in a decreasing or increasing manner upon irradiation, reaching a steady-state value. These new understandings suggest the importance of incorporating the effect of CSRO in investigating radiation-driven microstructural evolution.

Automated summary

Chemical short-range order (CSRO), a nanoscale atomic feature, has been shown to significantly affect defect properties and radiation behavior in Fe-Ni-Cr alloys. Molecular dynamics simulations reveal that random solutions, characterized by negative stacking fault energy, exhibit the strongest diffusion tendency, while high CSRO degrees reduce defect diffusivity due to trapping effects. In high-CSRO scenarios, interstitial clusters become Cr-rich and interstitial loops prefer Cr-rich CSRO domains. CSRO dynamically evolves during irradiation and reaches a steady-state value. These findings emphasize the importance of considering CSRO when investigating radiation-driven microstructural evolution.