| Author(s) |
Kevin Field, Pengyuan Xiu, T.M. Kelsy Green, Ethan M. Polselli, Weicheng Zhong, Kai Sun, Tim Graening, Niyanth Sridharan, Ying Yang |
| Abstract Scope |
Ensuring the long-term reliability of structural materials remains a cornerstone challenge for both fission and fusion energy systems. This talk focuses on the shared scientific foundation underpinning materials advancement for these extreme environments, spotlighting the synergy between experimental simulation complexities in fission-like (e.g., BOR-60 fast reactor) and fusion-relevant conditions. We present recent advances in additive-manufactured (AM) HT-9 ferritic/martensitic steels and castable nanostructured alloys, a reduced-activation variant class, interrogated by systematic ion irradiation studies. Both materials were subjected to rigorous experimental conditions using ex-situ and in-situ transmission electron microscopy (TEM) ion irradiation, exploring parameter sets spanning broad ranges of dose, temperature, and critically, helium concentrations—emulating, and in some cases exceeding, fission and fusion helium generation rates. These investigations unravel the complex, multi-physics evolution of defect sinks—such as dislocation networks and nano-precipitates—and map their central role in controlling and being influenced by point defect and cluster migration. By intentionally modulating experimental simulation complexity, we extract nuanced trends that inform microstructural design and guide alloy optimization strategies, particularly concerning initial sink strength and post-build processing variability (e.g., quenching characteristics). Our findings illuminate how sink strength and sink type (vacancy versus interstitial affinity) fundamentally influence the effects of complex processing, governing both the ballistic dissolution and back-diffusion of solutes to precipitates, as well as the formation and stability of irradiation-induced cavities. Ultimately, these coupled insights push towards a unified framework for high-chromium steel development across reactor platforms, supporting model-informed alloy design and paving the way for the next generation of radiation-tolerant steels. |