NiCoCr-based medium-entropy alloys with superior resistance to radiation hardening and helium cavity growth

In this work, three NiCoCr-based medium-entropy alloys (MEAs), i.e., NiCoCr, NiCoCrW0.1 and NiCoCrTi0.1, were irradiated with helium (He) ions at 400 degrees C and 700 degrees C to study the radiation hardening and He -induced cavity growth behavior. The typical quaternary FeCoNiCr alloy was irradiated similarly and eval-uated for comparison. Using transmission electron microscopy and nanoindentation measurements, He -induced microstructural evolution and mechanical changes were systematically investigated. Here we show that mitigated radiation hardening at 400 degrees C and cavity growth behavior at 700 degrees C were exhib-ited in the NiCoCr-based MEAs, in contrast to significant radiation hardening and He cavity growth of FeCoNiCr. Among the studied alloys, NiCoCrW0.1 displayed the best radiation hardening resistance, while NiCoCrTi0.1 presented the strongest tolerance in terms of He cavity growth. The underlying reasons were carefully analyzed based on the observed microstructures. Our results demonstrate the great potential of NiCoCr-based MEAs to function as critical nuclear structural components at relatively low and high temperatures.(c) 2022 Published by Elsevier B.V.