Microstructural evolution of compositionally complex solid-solution alloys under in-situ dual-beam irradiation.

• Two CCAs demonstrated reduced void swelling compared to less complex materials. • Increasing temperature from 500 to 600 °C slightly reduced swelling levels in CCAs. • Swelling levels increased significantly with temperature in pure Ni and Fe 56 Ni 44. • Measured stacking-fault energy (SFE) increased with Mn-content between CCAs. • Increased swelling corresponded to lower faulted loop sink strength, higher SFE. This work attempts to link the microstructural evolution of single-phase compositionally complex alloy (CCA) compositions under dual-beam irradiation to their Mn-content via the stacking-fault energy (SFE) and vacancy migration energies. Two alloys, Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35 , along with less compositionally complex pure Ni and Fe 56 Ni 44 binary were irradiated at 500 and 600 °C under dual-beam 1 MeV Kr2+ and 16 keV He+ heavy-ions up to 7 displacements per atom (dpa) with a He/dpa ratio of 0.75 %/dpa using in situ transmission electron microscopy (TEM). Due to the bubble-stabilizing effect of implanted He, bubbles were observed in all irradiations, and populations of faulted interstitial loops were characterized in Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35. A reduction in swelling was observed in the two CCAs compared to pure Ni and Fe 56 Ni 44. Although swelling increased from 500 to 600 °C in Fe 56 Ni 44 , Cr 15 Fe 35 Mn 15 Ni 35 and Cr 18 Fe 27 Mn 27 Ni 28 both swelled slightly more at 500 °C. This was attributed to the difference in vacancy mobility, stronger pinning effect of vacancies on He, and the sink strength of faulted dislocation loops. Faulted interstitial loops nucleated with a higher number density and dislocation line density in Cr 15 Fe 35 Mn 15 Ni 35 at both temperatures, and at 600 °C in both materials. The differences in faulted loop population and temperature effect on swelling are correlated to the Mn-content and the measured SFE (20.2 ± 6.7 mJ/m2 for Cr 18 Fe 27 Mn 27 Ni 28 and 9.2 ± 3.4 mJ/m2 for Cr 15 Fe 35 Mn 15 Ni 35). [Display omitted] [ABSTRACT FROM AUTHOR]