Irradiation effects on Al0.3CoCrFeNi and CoCrMnFeNi high-entropy alloys, and 316H stainless steel at 500 °C.

To evaluate the potential of high entropy alloys (HEAs) for nuclear applications, two HEAs, Al 0.3 CoCrFeNi and CoCrFeMnNi, and a conventional Type 316H stainless steel (SS) were irradiated with 1 MeV krypton ions at 500 °C up to 1 dpa, and examined in-situ with a transmission electron microscope (TEM). After irradiation, a high density of ordered L1 2 nanoparticles was observed in Al 0.3 CoCrFeNi. In contrast, no phase transformation was observed in CoCrFeMnNi and 316H SS. In the thin foil regions of TEM samples, stacking-fault tetrahedra were observed in the HEAs. In the thick foil regions, interstitial dislocation loops were observed for all alloys, and the areal loop density increased linearly with foil thickness. The Al 0.3 CoCrFeNi had the largest loop size (the lowest density), followed by the CoCrFeMnNi and then the 316H SS. The higher loop nucleation rate in the 316H SS was attributed to carbon content. The degree of irradiation hardening was slightly lower for the HEAs than for the 316H SS, which is a promising sign for the nuclear application of HEAs at high temperatures. Bright-field TEM micrographs of Al0.3CoCrFeNi, CoCrFeMnNi and 316H SS irradiated with 1 MeV Kr ions at 500 °C to 1 dpa. All images were taken at similar foil thickness near 110 zone axis with g = 200. The two high entropy alloys exhibited significantly larger size and smaller density of dislocation loops as compared with the 316H stainless steels. Image 1 [ABSTRACT FROM AUTHOR]