Ion-irradiation induced hardening and defect evolution in CoCrFeMnNi

The operating conditions of future nuclear reactors, both fission and fusion, still pose a number of materials challenges. In this context, the novel class of high-entropy alloys (HEA) attracts attention due to good mechanical properties and corrosion resistance as well as an - mostly hypothesized -improved irradiation resistance. In the present work the single-phase fcc HEA CoCrFeMnNi, produced by means of powder metallurgy, was ion-irradiated with Fe ions at RT, 300°C and 410°C up to 0.6 and 1 dpa, respectively, along with the austenitic stainless steel 316 serving as a benchmark. Transmission electron microscopy and nanoindentation were applied to study the irradiation-induced hardening and the evolution of the microstructure. While similar hardening is observed for the HEA compared to the benchmark material 316 at RT and 410°C, substantially higher hardening was observed at 300°C. The origin of the hardening will be discussed based on the microstructural evidence.