The stability and behavior of Cr-rich α' precipitates under cascade damage in Fe-15Cr-8Al ternary alloys: An atomic-scale simulation study

The formation of Cr-rich alpha' precipitates in irradiated Fe-Cr-Al alloys has been recognized as a leading microstructural feature causing significant radiation-induced hardening and embrittlement. In this work, the stability of a pre-existing alpha' precipitate under cascade damage and its effect on cascaded-induced defects in an Fe-15Cr-8Al ternary alloy were investigated through molecular dynamics simulations. We mainly focused on the behavior of Cr-rich precipitates under the different cascade conditions. This atomic-scale study of cascades, with and without a Cr-rich precipitate, showed that the interaction of cascade with the pre-existing precipitate slightly increased the number of surviving Frenkel pairs and enriched the level of Cr atoms as interstitials. In addition, the presence of the Cr-rich precipitate did not considerably affect the fraction of defects in clusters and cluster size. In turn, the 2-nm precipitate could be completely dissolved under intermediate-high energy cascades (30 and 50 keV), but large precipitates (with the diameters of 3 and 5 nm) exhibited only slight modifications. Moreover, the changes in the chemical composition and microstructure of the precipitate were discussed. The cascade significantly decreased the average Cr content in the precipitate (up to similar to 45%) with concomitant increases in the Fe and Al contents from the high-energy cascades. Also, it was of interest to note the amorphous transformation of a 2 nm Cr-rich precipitate occurred in the displacement damage. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the stability of pre-existing Cr-rich α' precipitates under cascade damage and their effect on cascaded-induced defects in irradiated Fe-Cr-Al alloys through molecular dynamics simulations. The results showed that the interaction of cascade with the pre-existing precipitate slightly increased the number of surviving Frenkel pairs and enriched the level of Cr atoms as interstitials. Furthermore, the presence of the Cr-rich precipitate did not considerably affect the fraction of defects in clusters and cluster size.