Abstract:
This work studied the effect of sequential irradiation by krypton and helium ions at room
temperature on the composition and structure of CoCrFeNi and CoCrFeMnNi high-entropy alloys
(HEAs). Irradiation of the HEAs by 280 keV Kr14+ ions up to a fluence of 5 × 1015 cm–2 and 40 keV
He2+ ions up to a fluence of 2 × 1017 cm–2 did not alter their elemental distribution and constituent
phases. Blisters formed on the nickel surface after sequential irradiation, where large blisters had
an average diameter of 3.8 µm. The lattice parameter of the (Co, Cr, Fe and Ni) and (Co, Cr, Fe,
Mn and Ni) solid solutions increased by 0.17% and 0.37% after sequential irradiation, respectively.
Irradiation by Kr ions led to a decrease in tensile macrostresses in the HEAs in the region of krypton
ion implantation (Region I) and the formation of compressive macrostresses in the region behind the
peak of implanted krypton (Region II). Sequential irradiation formed large compressive stresses in
Ni and HEAs equal to −131.5 MPa, −300 MPa and −613.5 MPa in Ni, CoCrFeNi and CoCrFeMnNi,
respectively, in the Region II. Irradiation by krypton ions decreased the dislocation density by
1.6–2.3 times, and irradiation with helium ions increased it by 11–15 times relative to unirradiated
samples for CoCrFeNi and CoCrFeMnNi, respectively. Sequentially irradiated CoCrFeMnNi HEA
had higher macrostresses and dislocation density than CoCrFeNi.
