Effects of applied strain on defect production and clustering in FCC Ni

Abstract

The structural materials of nuclear reactors are subjected to an environment of complex mechanical stresses, which has been reported to significantly affect the primary radiation damage suffered by the structure. In this study, we perform classical molecular dynamics simulations to study the effects of mechanical strains on the defect morphology due to primary radiation damage for a collision energy of 5 keV in face-centered cubic Ni. We consider the effects of four representative types of mechanical strains: hydrostatic, tetragonal shear, monoclinic shear, and uniaxial strains, and we discuss three aspects of the defect morphology: 1) time evolution of generated Frenkel pairs, 2) size distribution of defect clusters, and 3) fraction of clustered defects. We find that volumetric and anisotropic strains differently and significantly influence the primary radiation damage to the structure via affecting the intrinsic physical properties associated with the generation, formation, migration, or binding of Frenkel pairs; this result is generally consistent with those of many simulations. We believe our current study can aid in providing a fundamental mechanistic understanding of primary radiation damage in Ni-based alloys (for e.g., high-entropy alloys) as well as the subsequent long-term microstructural evolution.