Fundamentals of Deformation Mechanisms in Polycrystalline Superalloys

This report summarizes the progress made on the project FA9550-18-1-7000 from 2018 to 2022. The project has built a US-UK international collaboration on the deformation (yielding, creep, fatigue) mechanisms in the high-strength nickel-based superalloys used for turbine applications. The science of the time-dependent deformation mechanisms which are precursors to fatigue failure has been studied on new grades of superalloys carefully designed and selected for this project. The scientific aim was to better understand the mechanisms of deformation with atomic-scale chemical resolution. Several scientific advances have been achieved through this project, including a new understanding of the high-temperature failure of the APB and Complex Fault strengthening mechanism in Ni-based superalloys. Also the d development of multi-scale modelling approach for the prediction of mid-temperature mechanical properties in Ni-based superalloys. Several papers were published and are listed in the report.