LAUSR

Two Co-free multi-principal-element alloys (MPEAs), viz. single-phase face-centered cubic (FCC) Fe 30 Ni 30 Mn 30 Cr 10 and (Fe 30 Ni 30 Mn 30 Cr 10 ) 94 Ti 2 Al 4 (all in atomic percent) with FCC matrix containing Ni-Ti-Al enriched L1 2 (ordered FCC) secondary phase (γ′), have been developed and investigated. The alloys were ion irradiated at 300 ° C and 500 ° C to peak damage of 120 displacements per atom (dpa). Compared with the (Fe 30 Ni 30 Mn 30 Cr 10 ) 94 Ti 2 Al 4 alloy, in the Fe 30 Ni 30 Mn 30 Cr 10 alloy, the dislocation loops were smaller, with a higher number density. The difference in loop size between the two MPEAs was attributed to the addition of Ti to the matrix, which was anticipated to lower the stacking fault energy and stabilize the faulted Frank loops. The γ′ phase showed good stability under irradiation, with no new γ′ precipitation or growth in existing precipitates. Both alloys showed similar irradiation-induced hardening at 300 ° C, but the (Fe 30 Ni 30 Mn 30 Cr 10 ) 94 Ti 2 Al 4 alloy exhibited lower irradiation-induced hardening at 500 ° C compared with the Fe 30 Ni 30 Mn 30 Cr 10 alloy.