Irradiation-induced damage evolution in concentrated Ni-based alloys

Understanding the effects of chemical complexity from the number, type and concentration of alloying elements in single-phase concentred solid-solution alloys (SP-CSAs) on defect dynamics and microstructure evolution is pivotal for developing next-generation radiation-tolerant structural alloys. A specially chosen set of SP-CSAs with different chemical complexity (Ni₈₀Fe₂₀, Ni₈₀Cr₂₀ and Ni₄₀Fe₄₀Cr₂₀) are investigated using 1.5 MeV Mn ions over a wide fluence range, from 2 × 10¹³ to 1 × 10¹⁶ ions cm⁻² at room temperature. Based on an integrated study of Rutherford backscattering spectroscopy in channeling geometry and molecular dynamics simulations, the results demonstrate that Ni₄₀Fe₄₀Cr₂₀ is more radiation tolerant than Ni₈₀Fe₂₀, Ni₈₀Cr₂₀ and elemental Ni in the low fluence regime. While chemical complexity of this set of SP-CSAs is clearly demonstrated to affect defect evolution through suppressed defect production and enhanced recombination at early stages, the effect of the mixed ferro- and anti-ferromagnetic interactions is not the only controlling factor responsible for the improved radiation performance. The observed strong alloying effect on defect evolution is attributed to the altered defect migration mobilities of defect clusters in these alloys, an intrinsic characteristic of the complex energy landscapes in CSAs.