Crystal-orientation-dependence of irradiation damage in CoCrFeNiMn alloy under heavy ion irradiation at 500°C

As promising nuclear structural materials, high-entropy alloys have attracted extensive attentions due to their excellent anti-irradiation properties. In this work, the crystal-orientation-dependence of irradiation damage in equiatomic CoCrFeNiMn alloy, subjected to 2.5 MeV Fe²⁺ irradiation up to 15 dpa at 500 °C, was investigated using transmission electron microscopy (TEM). The 〈001〉-oriented grain exhibited the worst irradiation resistance, as evidenced by the densest 1/2〈110〉 perfect dislocations, the largest faulted loops and the greatest void swelling among all the damaged orientations. The 〈011〉 grain showed the lowest void swelling. Furthermore, the 〈111〉 grain exhibited faulted loops that were smaller in size and exhibited a higher density. Possible contributions to the orientation-dependent radiation damage of CoCrFeNiMn were discussed. The minimal damage observed in 〈011〉 grain can be attributed to its highest degree of channeling. It is also crucial to consider other contributing factors as well for 〈001〉 and 〈111〉 grains. This study underscores the importance of accounting for orientation when assessing the irradiation damage behavior of polycrystalline SP-CSAs with substantial grain sizes.