Microstructure and mechanical properties of high-energy proton irradiated CrMnFeCoNi alloy and CW-316L

The CrMnFeCoNi alloy and CW-316L stainless steel underwent irradiation at the ISAC-TRIUMF facility with high-energy protons between 400-480 MeV. Irradiation doses reached up to 1.88 DPA-NRT and 223 He appm, while maintaining an estimated average temperature of 120 °C and a peak of 480 °C. Subsequent mechanical properties were evaluated using the small punch test. At doses under 1.88 DPA-NRT, neither alloy showed significant hardening compared to their non-irradiated conditions, a result attributed to the irradiation temperatures and the pre-irradiation cold-worked microstructures. The CrMnFeCoNi alloy tested at the highest dose level showed greater hardening than CW-316L, although the number of samples tested at this dose was limited. Undeformed sections of the highest dose samples were analyzed using Transmission Electron Microscopy. The examinations revealed an average helium bubble size of 5 nm in the CrMnFeCoNi alloy, whereas the CW-316L alloy showed no resolvable helium or vacancy clusters under the same helium concentration. Frank loops were observed in both alloys, with CW-316L exhibiting loops up to 100 nm, significantly larger than the maximum of 20 nm in diameter loops in the CrMnFeCoNi alloy.