Microstructure investigations of Fe50Mn30Co10Cr10 dual–phase high–entropy alloy under Fe ions irradiation

Highlights: • FCC γ–γ, HCP ε–ε twinning structures and FCC γ–HCP ε co-existed structures of the Fe₅₀Mn₃₀Co₁₀Cr₁₀ DP–HEA remain stable under a displacement damage of 50 dpa. • No elemental segregation, no amorphization, no phase decomposition or incoherent precipitation after irradiation were detected. • Defects free channels (DFCs) and abundant Lomer–Cottrell (L–C) locks are observed in the irradiated samples after tensile deformation, and the immobile L–C locks restrict DFCs size. An Fe₅₀Mn₃₀Co₁₀Cr₁₀ dual–phase high–entropy alloy (DP–HEA) was irradiated at room temperature with 3 MeV Fe ions to a dose of 50 displacement per atom (dpa) . Potentials of special elemental designed DP–HEAs with low stacking fault energy (SFE) as promising candidate materials for future nuclear energy systems are evaluated. Transmission electron microscopy (TEM) analysis finds that FCC γ–γ, HCP ε–ε twinning structures and FCC γ–HCP ε co-existed structures of the DP–HEA, which correlate with the combined high strength and high ductility featured by this alloy, remain stable under a displacement damage of 50 dpa. No elemental segregation after irradiation was detected by energy dispersive spectroscopy. The results indicate that TWIP and TRIP mechanisms, owned by many other DP–HEAs, may still work effectively, and the materials still possess the merits of combined high strength and ductility brought by TWIP and TRIP mechanisms under irradiation conditions. Defects free channels (DFCs) and abundant Lomer–Cottrell (L–C) locks are observed in the irradiated samples after tensile deformation. The immobile L–C locks restrict DFCs growth, prevent the pile-up of dislocation along grain boundaries, thus sustaining dislocations in the grain interior. This study provides a new strategy to improve simultaneously the irradiation resistance and mechanical properties of structural materials by introducing the TWIP and TRIP mechanisms.