Irradiation-induced defect evolution in concentrated solid-solution alloys: a molecular dynamics perspective

Abstract This computational study delves into the intricate interplay of alloying elements on the generation, recombination, and evolution of irradiation-induced defects. Molecular dynamics simulations were conducted for collision cascades at room temperature, spanning a range of primary knock-on atom energies from 1 to 10 keV. The investigation encompasses a series of model crystals, progressing from pure Ni to binary concentrated solid solution alloys (CSAs) such as NiFe 20 , NiFe, NiCr 20 , and NiFeCr 20 CSA. We observe that materials rich in Cr actively facilitate dislocation emissions and induce the nucleation of stacking fault tetrahedra in the proximity of nanovoids, due to Shockley partial interactions. This result is validated by molecular static simulations, which calculate the surface, vacancy, and defect formation energies. Among the various shapes considered, the spherical void proves to be the most stable, followed by the truncated octahedron and octahedron shapes. On the other hand, the tetrahedron cubic shape is identified as the most unstable, and stacking fault tetrahedra exhibit the highest formation energy. Notably, among the materials studied, NiCr 20 and NiFeCr 20 CSAs stood out as the sole alloys capable of manifesting this mechanism, mainly observed at high impact energies.